df <- data.frame(site=c("GA","NY","BO","NY","BO","NY","BO","NY","BO","GA","NY","GA","NY","NY","NY"),purchase=c("a1","a2","a1","a1","a3","a1","a1","a3","a1","a2","a1","a2","a1","a2","a1"),happycustomer=c("n","y","n","y","y","y","n","y","n","y","y","y","n","y","n"))

library(ggplot2)
library(dplyr)
df  %>%
      group_by(site, purchase,happycustomer) %>%
      summarize(bin = sum(happycustomer==happycustomer)) %>%
      group_by(site,happycustomer) %>%
      mutate(bin_per = (bin/sum(bin)*100)) %>%
      ggplot(aes(site,purchase)) + geom_tile(aes(fill = bin_per),colour = "white") + geom_text(aes(label = round(bin_per, 1))) +
      scale_fill_gradient(low = "blue", high = "red")