one_of_n.r

library(tidyverse)
library(babynames)

babynames %>%
    filter(sex == "M") %>%
    mutate(endletter = str_sub(name, -1)) %>%
    group_by(year, endletter) %>%
    summarize(letter_count = n()) %>%
    mutate(letter_prop = letter_count / sum(letter_count), 
           letter_rc = case_when(
             endletter == "n" ~ "N",
             endletter == "e" ~ "E", 
             TRUE ~ "Other letters"
           ), 
           letter_rc = factor(letter_rc, 
                              levels = c("E", "N", 
                                         "Other letters"), 
                              ordered = TRUE)) %>% 
  ggplot(mapping = aes(x = year, 
                       y = letter_prop, 
                       group = endletter, 
                       color = letter_rc)) + 
  geom_line(size = 0.5) + 
  scale_y_continuous(labels = scales::percent_format()) + 
  scale_color_brewer(palette = "Set2") + 
  guides(color = guide_legend(nrow = 1)) +
  labs(x = "Year", 
       y = "Percent of newborn boys' names ending in this letter", 
       color = "Letter:",
       title = "ONE OF N",
       subtitle = "End-letters of boys' names in the U.S. since 1880", 
       caption = "Data: United States Social Security Administration. Graph: @kjhealy") + 
  theme(legend.position = "top")