Mean population density

population_density

stden <- crime_nys %>% 
    select(Year, Density.sq.mi) %>%
    group_by(Year) %>%
    summarise(Density.sq.mi=mean(Density.sq.mi))

p9 <- ggplot(stden, aes(x=Year, y=Density.sq.mi)) + 
    geom_line() +
    ggtitle('Population Density in New York State (minus NYC)') +
    xlab('Year') +
    ylab('Population Density (ppl/sq.mi)') + 
    theme_minimal()
p9