Distribution of Birth Year and Top 10 Participating Nations in Berlin Marathon 2014

setwd("~/")
bm <- read.csv("BerlinMarathon2014.csv", header=T)
library(ggplot2)
p <- ggplot(bm, aes(birth_date, ..density..))
p <- p + geom_histogram(binwidth=1, colour = "black", fill = "lightblue") + geom_density()
p + ggtitle("Distribution of Birth Year for the Berlin Marathon 2014") + xlab("Year of Birth") + ylab("Density")

# get the top 10 particpating nations
library(plyr)
top10 <- ddply(bm, "country" ,summarise, count = length(country))
top10 <- as.data.frame(lapply(top10, unlist))
top10 <- head(arrange(top10, desc(count)), n=10)

p <- ggplot(top10, aes(x = reorder(country, count, function(x) -x), y = count))
p <- p + geom_bar(colour="black", fill="lightblue", stat="identity", position="dodge")
p + ggtitle("Top 10 Participating Nations in Berlin Marathon 2014") + xlab("Country") + ylab("Particpants")