Summary of the scores:

 grades$`Total Score` %>% summary()
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    0.00   55.75   68.50   67.77   90.00  100.00

Histogram:

hist(grades$`Total Score`, 12)

Kenrel density estimate:

plot(density(grades$`Total Score`, na.rm=T, from=min(grades$`Total Score`,na.rm = T), to=100, bw=6.5), lty=1, col="blue",  ann=F)