scen2 <- scen

x <- 
  filter(scen, type == "alt") %>% 
  dplyr::summarize(n = sum(n), .by = c("scen", "year"))

ggplot(x, aes(x = year, y = n, col = scen)) +
  geom_shadowpoint()

y <- 
  pivot_wider(x, names_from = scen, values_from = n) %>% 
  mutate(d = (B - A) - (A - C))
