Google Ngram Viewer allows you to make those neat graphs, which show how often a particular phrase can be found in books published on given year.
These can be pretty interesting. You can try classic ‘good’ vs. ‘evil’ battles, or just whatever comes to mind.
This graph shows the advent of hobbits in the English fiction literature. I’m not sure why would their popularity decline in the last couple of years though!
That’s definitely something we could change.