I have just published a Google doc of eight years of Operating System, Browser and Mobile data for www.radionz.co.nz.
I have also included a couple of graphs such as this one showing the decline of desktop use (click to see a larger version).
There are other interesting trends - the decline of IE, the decline of the Windows desktop OS, and the rise of Chrome (all as a percentage of the market) are also evident in the data.
I have released this data under a Creative Commons Attribution-ShareAlike 4.0 International License, so please share links to anything you do with it in the comments below.