VIZ <- p_dat %<>%
  filter(type == "alt") %>% 
  dplyr::summarize(m = weighted.mean(m, n), n = sum(n),
                   .by = c("year", "mp", "exp_tot")) %>%  
  filter(year >= 2015) %>% 
  mutate(w_n = n / lag(n) - 1)
