I tried doing this with my own Last.fm data, if this slow badly coded Heroku app...

I tried doing this with my own Last.fm data, if this slow badly coded Heroku app is still live you can see mine: http://lastfm-seasonally.herokuapp.com/user/pvam

Basically, I listen to what I like to listen to no matter the season. If you have last.fm change the last slash in that URL with your username and after a couple minutes (it's single-threaded pulling API requests) it'll show your analysis.