ggplot: showing custom legend with multiple layers

Question

I have a ggplot with several layers of bars and points. I could not figure out how to correctly show the legend for each layer. Here is the code:

country <- c(rep(c("AA"), 4), rep(c("BB"), 4))
score <- c(1.3, 7.2, 4.9, 7.5, 6.8, 4.1, 4.9, 5.8)
y_axis <- c(rep(c("Score 2019", "Score 2020", "Group median", "Cluster average"), 2))

dt <- data.table(country, score, y_axis)


ggplot(, aes(country, score)) +
  theme_bw() +
  geom_bar(data=dt[y_axis=="Score 2019"], stat="identity", fill="grey", width=0.5) +
  geom_point(data=dt[y_axis=="Score 2020"], aes(shape="Score 2020"), color="green4", size=2) +
  geom_point(data=dt[y_axis=="Cluster average"], aes(shape="Cluster average"), color="orange", size=2) +
  geom_hline(yintercept=unique(dt[y_axis=="Group median"][,score]), size=1, color="red3")

Right now I only manage to have "Cluster average" and "Score 2020" to show up in the legend (with wrong colors). How can I correctly display all layers in the legend (score 2019 and 2020, median and average)?