Creating a panel in R

Question

I'm trying to convert a dataset into panel format. The data I'm working with is

structure(list(country = c("United States", "United Kingdom", 
"Austria", "Belgium", "Denmark", "France", "Germany", "Italy", 
"Luxembourg", "Netherlands", "Norway", "Sweden", "Switzerland", 
"Canada", "Japan", "Finland", "Greece", "Iceland", "Ireland", 
"Malta", "Portugal", "Spain", "Turkey", "Australia", "New Zealand", 
"South Africa", "Argentina", "Bolivia", "Brazil", "Chile", "Colombia", 
"Costa Rica", "Dominican Republic", "Ecuador", "El Salvador", 
"Guatemala", "Haiti", "Honduras", "Mexico", "Nicaragua", "Paraguay", 
"Peru", "Uruguay", "Venezuela, RB", "Bahamas, The", "Guyana", 
"Belize", "Jamaica", "Suriname", "Trinidad and Tobago"), X1991 = c(9.466697, 
12.70026, 8.609274, 20.67125, 15.27627, 14.1245, 12.99189, 25.79043, 
10.71286, 11.37589, 14.0621, 13.82597, 7.349475, 16.4783, 12.73535, 
14.38924, 27.59104, 14.33194, 15.68901, 28.87188, 21.96201, 25.08096, 
34.97078, 14.39485, 13.17188, 29.50947, 25.58341, 66.1963, 40.03492, 
18.65303, 37.1314, 26.03545, 34.6685, 37.50071, 51.26684, 56.18301, 
55.4749, 52.70173, 35.80688, 50.83774, 35.59387, 57.63879, 48.41096, 
36.21405, 33.7312, 32.10205, 56.92463, 38.82807, 45.00337, 39.88507
), X1992 = c(9.303763, 12.71461, 8.619309, 20.3533, 15.02731, 
14.21911, 13.05418, 25.14109, 10.90013, 11.32678, 14.67935, 14.35829, 
7.614027, 16.5854, 12.26784, 14.66753, 26.93018, 14.57369, 15.63351, 
28.97146, 21.53763, 25.21774, 35.19677, 15.1521, 12.95588, 29.59264, 
24.56502, 67.0313, 40.36927, 18.53474, 37.38464, 24.96722, 32.38129, 
36.48993, 50.49888, 56.00072, 59.86622, 52.75889, 35.79857, 50.38135, 
36.8462, 57.65486, 47.12524, 36.15137, 33.88679, 31.63787, 51.55106, 
36.66505, 44.46601, 40.3785), X1993 = c(9.080958, 12.59956, 9.139214, 
20.91108, 15.80189, 15.27437, 13.32703, 26.21944, 10.84987, 11.49481, 
14.7627, 15.21175, 7.555834, 16.26694, 11.47213, 14.70983, 27.66412, 
15.02242, 15.59284, 30.25143, 22.45989, 26.36887, 34.76507, 14.89417, 
12.47009, 30.37844, 26.86143, 67.96336, 40.53667, 18.80095, 36.39204, 
24.87246, 32.4833, 37.03465, 48.94035, 55.78872, 54.69871, 51.77866, 
33.6244, 50.26001, 36.10211, 57.86855, 47.63047, 36.15184, 33.34574, 
31.5308, 53.17212, 37.91241, 43.06372, 40.17129), X1994 = c(8.781489, 
12.25241, 9.041289, 20.3745, 15.08438, 14.87908, 13.0522, 25.1567, 
10.49054, 11.27928, 14.48236, 14.32798, 7.425584, 15.64039, 10.76084, 
14.03636, 27.15211, 14.84825, 15.35435, 30.17439, 22.14262, 25.68533, 
33.4688, 14.21835, 11.76606, 30.34188, 26.26593, 68.00209, 38.37244, 
18.59566, 36.10671, 25.05978, 32.41806, 36.62653, 47.8913, 54.5767, 
62.74195, 50.60651, 33.54415, 46.05959, 35.54406, 57.75067, 46.24404, 
35.9547, 34.24746, 31.78871, 53.29678, 35.10365, 41.58193, 38.70048
), X1995 = c(8.545056, 11.49745, 8.739349, 19.58722, 14.34322, 
14.24083, 12.46833, 23.11267, 10.50515, 10.80974, 14.11158, 13.25241, 
7.109927, 15.03751, 9.861328, 13.1955, 27.23854, 14.70156, 14.78404, 
28.03427, 21.25489, 24.75413, 31.87565, 13.59488, 11.67493, 27.78184, 
26.29767, 67.35535, 41.47369, 17.98568, 36.13323, 24.62439, 32.26373, 
36.37431, 46.79122, 53.57656, 56.08898, 49.39904, 34.58409, 45.48735, 
35.37595, 57.78064, 45.90767, 35.89915, 33.50277, 31.54198, 51.35318, 
34.54484, 42.43228, 39.03833), X1996 = c(8.48449, 11.32384, 8.832439, 
19.91044, 14.59947, 14.26158, 12.98375, 21.9484, 10.8005, 10.80392, 
13.48495, 13.47378, 7.15642, 14.89334, 10.96183, 13.46861, 26.26522, 
14.63233, 14.67937, 29.59633, 20.83297, 23.70248, 32.34503, 13.58493, 
11.66051, 29.64024, 24.87034, 64.87973, 40.59486, 18.92373, 37.96582, 
24.37223, 31.74271, 35.28242, 48.41487, 54.42724, 61.36868, 48.76796, 
33.98355, 44.06224, 36.20663, 58.11508, 47.64743, 33.19671, 33.12061, 
30.87537, 49.90856, 35.72561, 42.47012, 37.85729), X1997 = c(8.054869, 
10.83358, 8.935195, 19.94567, 14.32995, 14.60135, 12.90728, 23.14226, 
10.77988, 10.632, 13.03157, 13.11257, 7.140849, 14.0945, 11.6737, 
13.07841, 26.86832, 14.32839, 14.19622, 28.48682, 21.25549, 24.20675, 
31.73924, 12.95593, 11.80613, 29.14469, 25.04493, 67.03664, 39.91468, 
18.42755, 38.1356, 23.92611, 32.49583, 36.07079, 46.18186, 52.31389, 
57.81606, 47.83242, 32.15459, 44.46477, 37.6049, 57.42832, 43.35729, 
37.5862, 28.94877, 31.80715, 51.22635, 36.13396, 42.06123, 38.62755
), X1998 = c(7.917026, 10.64952, 8.840578, 20.25051, 14.62852, 
14.01576, 12.67833, 22.30755, 10.47956, 10.5699, 13.58033, 13.25664, 
6.843061, 14.04881, 12.4501, 12.69239, 26.37329, 14.15909, 13.79035, 
28.33476, 20.70496, 23.31775, 31.21666, 12.88887, 12.13158, 28.63219, 
24.37831, 65.08696, 40.71648, 19.01768, 39.0377, 22.79442, 31.73241, 
35.51129, 46.67567, 52.59356, 56.18784, 47.91514, 32.15557, 44.09471, 
38.04431, 59.02924, 43.32638, 37.69873, 27.82917, 31.68645, 49.87334, 
36.40297, 42.27305, 36.71758), X1999 = c(7.785953, 10.81852, 
8.961732, 19.89368, 14.56036, 13.95977, 12.76503, 22.95276, 10.07463, 
10.40416, 13.76689, 12.95814, 6.985637, 13.62815, 11.70907, 12.6525, 
26.57231, 14.26858, 13.44808, 27.63038, 21.06183, 23.49881, 33.28962, 
13.42659, 11.72431, 29.05433, 25.91528, 68.97253, 41.22367, 19.3233, 
40.08756, 24.09756, 32.39124, 37.48175, 46.76992, 53.09169, 53.90523, 
49.28431, 31.60043, 44.01134, 39.0433, 59.99107, 45.73804, 38.33972, 
27.0813, 32.46339, 47.90463, 36.22794, 40.44304, 37.71281), X2000 = c(7.6, 
10.8, 8.8, 19.9, 14.6, 13.8, 12.9, 22.7, 9.8, 10.5, 12.7, 12.6, 
6.8, 13.4, 11.2, 12.5, 26.1, 14.3, 13.4, 27.1, 21.4, 22.7, 32.1, 
13.1, 11.5, 28.4, 25.4, 67.1, 39.8, 18.9, 39.1, 23.9, 32.1, 34.4, 
46.3, 51.5, 55.4, 49.6, 30.1, 45.2, 39.8, 59.9, 46.1, 36, 26.2, 
33.6, 43.8, 36.4, 39.8, 34.4), X2001 = c(7.79688, 10.9712, 8.602537, 
20.05741, 14.5474, 13.72839, 12.71711, 23.69607, 10.33013, 10.50796, 
12.90929, 12.7768, 6.949753, 13.58013, 12.32607, 12.57916, 26.63951, 
14.65992, 13.24933, 28.54649, 21.83641, 23.19855, 32.80612, 12.79749, 
11.25358, 29.05607, 26.43108, 70.52103, 39.93838, 18.99352, 37.87475, 
24.73318, 32.94988, 35.06028, 46.40176, 53.75644, 57.66782, 50.43951, 
30.4776, 43.86853, 39.2034, 59.88477, 46.81207, 38.24242, 27.00889, 
33.84821, 45.14941, 36.4029, 40.43658, 36.00584), X2002 = c(8.065814, 
11.05188, 8.36268, 20.13254, 14.58564, 14.4721, 12.80952, 23.00992, 
10.24801, 10.78021, 14.18768, 13.09282, 7.085135, 13.9569, 12.99939, 
12.74684, 26.449, 14.76287, 13.21066, 27.80897, 21.2177, 22.6747, 
32.90903, 12.75904, 11.41571, 29.41586, 28.50171, 69.33923, 40.52047, 
18.89015, 38.53525, 24.30426, 33.14258, 34.55454, 45.65086, 52.46833, 
59.98206, 50.00206, 30.20463, 44.09079, 39.00892, 58.21494, 47.9141, 
37.36144, 26.15215, 33.99278, 45.97421, 36.24654, 39.82333, 34.96064
), X2003 = c(7.92499, 10.75462, 8.016287, 19.3969, 13.9228, 13.61119, 
12.21044, 22.02622, 10.15476, 10.41062, 13.96429, 12.44403, 7.002441, 
13.68019, 12.36653, 12.0935, 24.69863, 14.25037, 13.00581, 26.92164, 
20.57124, 21.4388, 31.35238, 12.44689, 11.12067, 28.47548, 27.78965, 
69.93862, 39.93658, 18.46029, 36.84313, 23.93652, 32.42342, 34.92994, 
44.5533, 53.12335, 57.98775, 49.39722, 31.32375, 43.04076, 38.10376, 
58.16525, 46.39695, 37.48957, 26.42809, 34.8031, 45.38447, 36.54242, 
38.99598, 33.8569), X2004 = c(7.84487, 10.38025, 7.623134, 18.25984, 
13.15906, 12.55085, 11.20118, 21.05232, 9.785735, 9.793324, 12.63204, 
11.43552, 6.624626, 13.09116, 11.49399, 11.50284, 23.22433, 13.14459, 
12.50019, 27.13683, 19.85981, 20.89485, 29.76571, 12.22817, 10.74906, 
26.6909, 26.99339, 69.13512, 38.47203, 17.1794, 36.27291, 23.77458, 
32.19539, 34.09993, 43.56797, 50.51601, 54.09277, 47.5024, 29.83703, 
43.32811, 37.01172, 56.08345, 44.38279, 35.41991, 26.29085, 34.46201, 
44.71092, 34.19681, 38.5186, 32.95794), X2005 = c(7.409073, 10.25542, 
7.641707, 18.1067, 12.58107, 12.45072, 10.94004, 21.23636, 9.764019, 
9.558563, 11.75198, 11.39954, 6.405988, 12.65939, 11.52433, 11.30194, 
23.54169, 12.1181, 12.15365, 25.81203, 20.00584, 20.58528, 28.76027, 
12.14793, 10.9936, 26.1569, 26.27867, 67.46194, 38.46534, 16.40009, 
33.68972, 23.16504, 31.50445, 32.96735, 43.444, 50.44918, 54.71084, 
47.20681, 28.68776, 41.66956, 36.84262, 56.56807, 43.44911, 33.32873, 
25.13837, 34.6515, 44.25949, 34.28978, 37.93071, 32.05394), X2006 = c(7.087106, 
9.416714, 7.280048, 17.67059, 11.83569, 11.77265, 10.03901, 20.52238, 
9.0893, 9.401095, 10.78442, 10.70523, 6.054787, 11.98443, 11.57119, 
10.86325, 22.52329, 12.03551, 11.76605, 25.09538, 19.62627, 19.94487, 
28.9095, 11.61166, 11.29373, 22.79942, 25.74977, 63.3251, 37.33846, 
15.38923, 31.87442, 22.94466, 30.9838, 32.34629, 43.0243, 49.5191, 
53.44281, 47.32837, 28.11041, 42.41487, 36.11888, 54.13265, 42.72568, 
32.91296, 25.12673, 30.58285, 41.8187, 32.53089, 37.12317, 32.24378
), X2007 = c(6.977391, 9.073042, 6.440911, 16.05915, 11.15295, 
10.82276, 8.895263, 18.44522, 8.067305, 8.813849, 10.33178, 9.636645, 
5.480703, 11.60734, 11.52385, 10.11268, 20.91588, 10.87782, 11.37027, 
23.2463, 18.03865, 18.70368, 28.14933, 11.13735, 10.7289, 22.48885, 
24.85482, 61.64273, 35.91535, 14.95068, 31.33743, 22.69258, 30.39451, 
31.78927, 42.05253, 48.84175, 55.66379, 46.70432, 27.68513, 41.29661, 
34.48414, 52.09107, 41.94362, 32.41677, 24.56788, 29.30938, 42.56357, 
32.15828, 35.87257, 31.21319), X2008 = c(7.04429, 9.43901, 6.38459, 
15.54989, 10.92755, 10.13004, 8.724296, 18.08489, 7.908217, 8.40461, 
9.363515, 9.522866, 5.258641, 11.47849, 10.66823, 9.661416, 19.71202, 
11.95845, 11.80091, 23.16899, 17.18026, 18.5618, 26.89617, 10.31971, 
10.89236, 23.47075, 23.75576, 57.95301, 33.58034, 14.9278, 28.92132, 
22.06987, 30.31432, 30.78528, 41.35677, 48.24676, 51.22517, 46.13977, 
28.12636, 39.85336, 31.82907, 49.75977, 40.24143, 30.51808, 25.60552, 
29.32154, 41.80352, 31.03301, 33.45311, 28.9401), X2009 = c(7.778797, 
10.70226, 7.843618, 17.42381, 13.27648, 12.12527, 11.04455, 21.18228, 
9.205264, 9.420588, 12.41037, 11.49191, 5.965051, 13.16644, 11.02698, 
11.31168, 22.84254, 13.88099, 12.56331, 23.97882, 19.11955, 21.27849, 
30.59277, 10.92427, 11.68721, 25.56405, 25.34736, 61.66948, 35.06244, 
16.68009, 31.41242, 23.73957, 31.75765, 33.93108, 44.66014, 50.19032, 
51.19785, 49.11882, 31.3617, 40.84897, 34.57714, 51.74541, 41.54239, 
33.06199, 28.34197, 29.0305, 46.00201, 35.38446, 34.80878, 32.86263
), X2010 = c(7.376719, 10.26104, 7.619407, 16.8767, 12.99496, 
11.76674, 10.55666, 20.76782, 8.844535, 9.383975, 11.72676, 10.2867, 
5.583534, 12.20572, 9.990183, 11.14735, 23.06686, 13.51006, 12.28003, 
23.54159, 18.58213, 21.3453, 28.47879, 11.05288, 11.03802, 23.67422, 
23.32711, 58.07549, 30.79277, 15.21584, 29.86559, 23.44928, 30.33589, 
31.84342, 43.22049, 48.19894, 49.23256, 46.70935, 29.19339, 39.94398, 
32.21785, 47.23038, 38.76082, 29.29831, 28.26289, 27.72336, 44.97131, 
34.48751, 32.90122, 31.71356), X2011 = c(6.974901, 9.860477, 
6.911301, 15.96001, 12.01377, 11.14819, 9.465784, 18.89686, 8.37791, 
8.874323, 10.8663, 9.531965, 5.145397, 11.68337, 9.283687, 10.55069, 
23.01675, 12.91455, 11.95498, 23.14987, 17.62694, 20.62391, 26.18048, 
10.10176, 10.3481, 21.87501, 21.48915, 54.45123, 28.16069, 14.14179, 
25.74275, 23.11348, 29.23334, 30.00691, 40.81779, 46.61397, 48.43871, 
43.37913, 27.7228, 37.33601, 30.993, 44.37486, 36.90338, 31.21417, 
28.69313, 26.8794, 42.84438, 32.51071, 31.64605, 30.15389), X2012 = c(6.657509, 
9.732188, 7.033195, 16.74617, 12.43732, 11.70657, 9.852426, 20.00195, 
9.015792, 9.113639, 10.8151, 10.22781, 5.330751, 11.57646, 9.150372, 
11.11851, 24.34838, 12.93617, 12.03917, 23.76534, 17.70507, 21.30682, 
26.53366, 9.760859, 10.35463, 23.30132, 22.01249, 52.01794, 29.10422, 
14.0706, 25.22406, 22.35607, 28.9937, 29.66566, 40.18313, 46.79844, 
48.26965, 44.46917, 27.67793, 36.40452, 33.03363, 43.59267, 37.35012, 
29.70259, 27.98101, 25.48819, 41.40083, 32.58753, 30.72083, 30.13495
), X2013 = c(6.554123, 9.494184, 6.951313, 16.55417, 11.90497, 
11.63573, 9.908278, 20.00587, 8.690906, 8.953243, 10.89887, 10.23386, 
5.272172, 11.51927, 10.65292, 11.09442, 23.70539, 12.66498, 11.71287, 
22.57655, 17.49627, 21.10978, 25.83731, 9.774403, 9.912015, 24.10841, 
22.15492, 51.11789, 29.34299, 14.3229, 25.75971, 22.19389, 28.59511, 
29.18457, 39.56124, 46.72985, 47.48047, 45.82622, 27.4439, 35.66434, 
31.05534, 44.03198, 36.92328, 29.72047, 27.84786, 26.14193, 41.23128, 
32.60809, 30.2696, 29.26605), X2014 = c(6.132558, 8.74118, 6.565069, 
15.94421, 11.143, 11.35683, 9.195051, 19.68568, 7.881455, 8.57969, 
11.05476, 10.12535, 5.133912, 11.06093, 10.75961, 10.57897, 23.56525, 
12.12985, 10.96167, 21.88125, 16.70176, 20.86857, 26.20802, 9.401912, 
9.456337, 24.68061, 23.05032, 50.68767, 29.85044, 14.77783, 25.97198, 
21.96381, 27.9705, 29.19074, 38.55982, 44.77505, 46.72801, 42.87592, 
26.61818, 35.17437, 30.69654, 45.55032, 36.27272, 28.7086, 27.11356, 
26.67674, 41.12282, 31.91752, 30.70036, 28.88761), X2015 = c(6.067053, 
9.157207, 7.321307, 17.19869, 12.00361, 12.22882, 10.23155, 20.86162, 
8.486896, 9.012305, 12.49535, 10.66562, 5.383994, 12.11699, 11.66842, 
11.51147, 25.28144, 12.21772, 9.527719, 21.47827, 17.42518, 21.94668, 
27.74263, 10.537, 10.02411, 26.00351, 22.42759, 57.09551, 33.64449, 
15.89266, 28.6472, 21.70943, 28.60248, 31.03963, 38.8336, 43.44925, 
47.2543, 41.48793, 28.0199, 35.11555, 32.58381, 46.94251, 37.86011, 
33.65513, 27.36985, 26.36789, 41.00148, 31.45438, 32.05307, 29.88863
), X2016 = c(5.895523, 9.733155, 7.422861, 16.89989, 12.09571, 
12.17662, 10.70104, 20.61189, 8.748249, 9.094771, 13.08558, 10.86668, 
5.428309, 12.34815, 11.10728, 11.40616, 25.4206, 11.6018, 9.673442, 
20.14576, 17.14884, 21.28021, 29.14289, 11.83565, 10.09793, 27.25887, 
22.30683, 58.21952, 34.56264, 16.90466, 30.0254, 21.38795, 27.491, 
31.33347, 39.1108, 43.36517, 47.88132, 42.57794, 28.80232, 34.08224, 
32.274, 47.30967, 40.17884, 34.76456, 27.62428, 24.77209, 43.92677, 
31.74779, 35.26232, 31.74227), X2017 = c(5.693526, 9.423729, 
7.053332, 16.45845, 11.69496, 11.71508, 10.37214, 19.82095, 8.768428, 
8.820032, 12.72126, 10.74856, 5.433295, 12.04029, 10.77753, 10.77638, 
24.76788, 10.78062, 9.582448, 18.61635, 16.12002, 20.32123, 28.61489, 
11.61703, 9.720349, 26.87041, 20.85126, 55.77534, 33.78638, 16.77554, 
29.94245, 21.24196, 27.48569, 30.59406, 39.15396, 42.02414, 47.16809, 
40.98615, 28.06211, 33.83511, 30.9853, 45.88619, 39.68999, 35.40468, 
27.96575, 24.5137, 43.74885, 29.86539, 35.70398, 31.40351)), row.names = c(NA, 
50L), class = "data.frame")

All values are for the same variable.

I would like the panel to be standard, meaning to have an id column, a year column and column with the variable values.
The idea is to be able to merge the result from this with another panel using as keys the country and year. So I basically need to have a resulting panel with 3 columns (country, year, value) from this data.

Any help would be much appreciated!