The topic of ratings is something I find very interesting, because I'm not sure what leads players to rate a game. ¿?
In fact, I have a few more followers than the OP, and my project with the most ratings has only 4. (All 5-star ratings, quite a few comments, 29 collections, and veryp positive “external” feedback but)... ONLY 4 RATINGS.
I also find very interesting the ratio followers / ratings you've mentioned, I've never heard about it.
Have a nice day mate.