Comment Reality: (Score 3, Insightful) 160
The reality is that those numbers don't really matter if you already have a website.
You can easily run stats on YOUR OWN WEBSITE and get the browser breakdown that you should be worried about.
For one of my primary sites, all version of IE beat out Firefox or Chrome. When split apart, Firefox and Chrome are 1 and 2, with IE8 coming in third.
And now that I think about it, knowing who is first or second is pretty much irrelevant. What matters is the percentage of users who are still using browser version that suck to support. So really, what I care about is where my IE7 and IE6 usage is, and at what point is it okay for me to walk away from those users.