This is a follow-up question of sorts to

CodePudding user response：

To get cumulative figures the easiest way is to repeat each month's data in future months.

Using the tidyverse, add the following statement before you define p...

points <- points %>% 
  mutate(monthly = map(monthly, ~seq(., max(monthly), by = "month"))) %>% 
  unnest(monthly)

Note that a cumulative density will not necessarily increase over time - if you want an animation that steadily increases you might want to add contour_var = "count" to your geom_density... term.