Chapter 2 Probelm 2

ggplot(mpg, aes(x=hwy, fill=drv))+
  geom_histogram(alpha=0.5)+
  facet_grid(drv~.)+
  theme_minimal()+
  labs(title = "Histogram using facet_grid", subtitle = "Histogram of Highway Miles Per Gallon", x="hwy", y="count",caption ="Source=mpg")

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.