Visualizing with {ggplot2} package

library(ggplot2)
# build a dataframe:
n=length(r99ptot.71.00)
dat<-data.frame(
  dens=c(r99ptot.71.00,r99ptot.61.90),     lines=rep(c("r99ptot.71.00","r99ptot.61.90"),each=n)
  )

ggplot(dat, aes(x = dens, fill = lines)) + geom_density(alpha = 0.5)
## Warning: Removed 4 rows containing non-finite values (stat_density).