Histogram as Percentage

library(tidyverse)
library(gridExtra)


plot1 <- ggplot(mtcars, aes(x = hp)) +  
    geom_histogram(bins = 10) +
    labs(
        y = 'Count of Awesomeness',
        title = 'Count Histogram'
    )


plot2 <- ggplot(mtcars, aes(x = hp)) + 
    geom_histogram(bins = 10, aes(y = stat(width*density))) +
    scale_y_continuous(labels = numform::f_pp) +
    labs(
        y = 'Percentage Awesomeness',
        title = 'Percentage Histogram'
    )

grid.arrange(plot1, plot2, ncol = 1)