> H2 = c(2700,2600, 3050, 2900, 3000, 2500, 2600, 3000, 2800,
+ 3200, 2800, 3400)
> cumsum(H2)
[1] 2700 5300 8350 11250 14250 16750 19350 22350 25150 28350
[11] 31150 34550
> diff(H2)
[1] -100 450 -150 100 -500 100 400 -200 400 -400 600
We see that there were 34,550 sold, December had the greatest
increase (600), and June had the largest decrease (-500).