First make up some data to test.
library(ggplot2)
age<-10:45
asymptote<-2000
half<-20
coolness<-asymptote*age/(half+age)+rnorm(36,0,20)
d<-data.frame(age,coolness)
g0 <- ggplot(d, aes(age, coolness))
g1<-g0+ geom_line() + theme_bw()
g2<-g1 + coord_polar(theta = "x")
g2
The more usual way of showing this is as line.
g1