Is it possible to have x axis ticks and labels for no data points in ggplot to show only one x-axis result?

Question

I\'ve got a data set of

Target_num <- c(40, 40, 40, 40, 40, 40, 120, 120, 120, 120, 120, 120, 160, 160, 160, 160, 160,160,160, 200, 200, 200, 200, 200, 200, 24