df = read.csv(file = "SP500.csv", header = TRUE, sep = "\t", stringsAsFactors = FALSE)
SP500 = as.numeric(sub("%", "", df$S.P.500..includes.dividends.))
mean(SP500)

## [1] 11.53

sd(SP500)

## [1] 19.62138

library(ggplot2)
ggplot(data.frame(SP500), aes(x = SP500)) + geom_histogram(bins = 30, aes(y=..density..),) + geom_density(alpha=.2, fill="#FF6666")