Hell, I sound like clickbait, but this thing is pretty cool:
https://research.google.com/bigpicture/music/#
So it gives a graph showing the relative popularity of different types of music from 1950-current day. When you first see it, there are the basic genres - rock, jazz, pop… but the interesting thing is what happens when you click on one of the genres.
I’ll shut up now and let y’all play with it, but this is a good resource for discussions about post-1950 music history, when particular styles were popular, and their relative popularity vis-a-vis other styles. You can even type in artists names in the top right and see their chart success history.
I’m 99% sure this is based on American charts only.
Lastly, if you are a Twitter user and you like geeky charts and cool data representations like this, follow Linda Regber’s account - she finds some great, obscure data and charting work https://twitter.com/LindaRegber