Is there publicly available data somewhere with estimates on the number of users of each Mac OS X version? Particularly for the major releases (10.6.* Snow Leopard, 10.5.* Leopard, ...)?
I am writing a new application and am wondering whether it's still worth the effort of supporting pre-Leopard versions of Mac OS X, mostly Tiger. I am using Sparkle with the option of tracking system profiles with every update check, but as the application is still in early 0.* releases the number of users so far is so small it's hardly statistically relevant. The application is built to support Tiger and up, but I have not yet seen a Tiger user in the system profiles yet.
I realise there are some other factors at play too besides the number of users to decide whether to still support an older release. For example, I waited a long time to upgrade to Leopard myself, and at some point I got so used to seeing "requires at least Mac OS X 10.5" that I stopped looking for new applications altogether. I expect that's similar for anyone else still using Tiger.
Still, would be nice to have the data. Also just out of curiosity ... anyone seen someone still using Cheetah lately? ;)
This question comes up reasonably often, and the best data is probably Sparkle stats, which is no doubt slightly skewed towards more tech-savvy users. Of course, this may be fine if that's your target market!
OmniGroup also provides stats from their updater: http://update.omnigroup.com/ The numbers are quite different to Sparkle's, and the graph of users over time indicates a slow decline for 10.4 (30%), a fast decline for 10.5 (25%), and a fast uptake of 10.6 (45%).
Finally, http://macosxhints.com has run a few polls recently about OS version and hardware type:
Their numbers are similar to those from Sparkle, although they are self reported. Most interestingly though, they show 45% of users who still own/use a PPC Mac, and just over 7% have Hackintoshes.