This morning I listened to episode 93, and I heard Joe talking about the number of books that he rated below a certain rating. So I spent an hour and a half visualising all the ratings they gave for every Bookworm episode. Code and visualisations also available at https://github.com/andrewjpfeiffer/ref-bookworm. Hope you find this helpful!
Visualisation of Bookworm ratings
Nicely done. I was just looking for something like this.