Unable to print Curve fitting in python

Question

Hi i have following dataframe.

    Years  Count
0    2003     99
1    2004    116
2    2005    101
3    2006    115
4    2007    108
5    2008    122
6    2009    162
7    2010    152
8    2011    221
9    2012    252
10   2013    351
11   2014    480
12   2015    409
13   2016    384
14   2017    581
15   2018    406
16   2019     18

I am trying to plot curve fitting for this one. but i am not sure what mistake i m making. Its not printing curve fitting. You can place the above given dataframe in the code marked location. initiall it did plot the graph correctly but after that it didn't i have even try to restart anaconda but still its not printing.. It could be some very minor mistake...

from numpy import arange
from pandas import read_csv
from scipy.optimize import curve_fit
from matplotlib import pyplot
import pandas as pd
import matplotlib.pyplot as plt

##(place above given dataframe here)
dff.plot(x='Years',y='Count', marker = 'o')
print(dff)


x= dff.iloc[:, 0]
y= dff.iloc[:, 1]


def objective(x, a, b, c, d, e, f):
    return (a * x) + (b * x**2) + (c * x**3) + (d * x**4) + (e * x**5) + f

popt, _ = curve_fit(objective, x, y)           
a, b, c, d, e, f = popt                         

pyplot.scatter(x, y)                        
x_line = arange(min(x), max(x), 1)        
y_line = objective(x_line, a, b, c, d, e, f)    
pyplot.plot(x_line, y_line, '--', color='red') 
pyplot.show()

Required Plot