This changes the turns per year to 12. It also changes the months/seasons to work correctly. For technical reasons, the new year starts in March instead of January.
Mod - http://www.mediafire.com/file/7sm5wy...0%4012TPY.pack
Steam - https://steamcommunity.com/sharedfil...?id=1379021244
If you want the seasons to have a bit more impact, I recommend using this with the Season Effects mod.
*If you are using a game version other than english, the months will be off (it will start in January) unless you get a translated version of the text files.