Relative usage of the exclamation point
The graph below shows the number of times the exclamation mark (!) appears as a fraction of single words (that is, 1-grams) by year in American, British and German texts, according to data from Google Books.
(click image to enlarge)
It’s interesting to see in places where, in times of war, for example, the usage of exclamation points tends to rise. We can see this in works published in American English during the US Civil War (1861 through 1865) as well as in German texts starting in 1914. In both cases, there does not appear to be an increase in the frequency of exclamation points leading up to the starts of those wars, though personally I would have expected that.
We can also actually see the rising usage of exclamation points in German text from 1933 right through the end of the war. So, while historians pin the start of World War II to Germany’s invasion of Poland in September 1939, from Hitler’s perspective it seems to have started right from the moment he came to power.
Interestingly, the British seem to have become more reserved during World War I and the Second World War, with their usage of the exclamation point dipping, rather than rising, in each case. American usage seems oddly unaffected by WWI (though this might be due to the US’s short involvement).
Notably, even at the peak of World War I, the frequency of German usage of exclamation point never reaches American levels. In times of peace Americans were more ebullient than Germans in times of war.
After the Second World War, usage of the exclamation point dropped in all three bodies of texts to a low point by 1980. (I cut off the graph at that point, but usage levels remained basically unchanged in all three languages throughout the 1980s and 1990s.) People complain about news broadcasts being so sensationalistic these days, but when it comes to books, at least, we are less sensationalistic now than ever.
Some parts of the trends remain unexplained in my mind, though. For example, the run-up in American usage of the exclamation point from about 1887 through 1893. I think I should look more into financial crises as well as British wars in the 1800s.