VIZ <- 
  left_join(
    filter(pen_n, type == "wit", sex == "f", nat == "ch") %>% 
    dplyr::summarize(n = sum(n), .by = c("year", "age")),
    filter(pop, sex == "f", nat == "ch") %>% 
      dplyr::summarize(pop = sum(pop), .by = c("year", "age")),
  by = c("year", "age")) %>% 
  mutate(share = n / pop) %>% 
  mutate(coh = year - age) %>% 
  filter(coh %in% 1933:1936)

ggplot(VIZ, aes(x = age, y = share, col = as.factor(coh))) +
  geom_shadowpoint()

  