```r
year_term_counts %>%
  filter(term %in% c("god", "america", "foreign", "union", "constitution", "freedom")) %>%
  ggplot(aes(year, count / year_total)) +
  geom_point() +
  geom_smooth() +
  facet_wrap(~ term, scales = "free_y") +
  scale_y_continuous(labels = scales::percent_format()) +
  ylab("% frequency of word in inaugural address")
```

<div class="figure">
<img src="05-document-term-matrices_files/figure-html/yearterm-1.png" alt="Changes in word frequency over time within Presidential inaugural addresses, for six selected terms" width="672" />
<p class="caption">(\#fig:yearterm)Changes in word frequency over time within Presidential inaugural addresses, for six selected terms</p>
</div>