IE6 is the worst thing about creating sites right now.
FF 2.0.x.x 7.5%[1], other FF 1.9%, total FF 9.4%
Others 6.1%[2]
1. FF 2.0.x.x number has been arrived by adding the percentages of the seperate versions, so there's some rounding error there. Other FF has been arrived at by subtracting FF 2.0.x.x from total FF (which is accurate).
2. Similarly others has been derived by subtracting the totals for IE and FF from 100.
You might also find this page useful:
http://www.w3schools.com/browsers/browsers_stats.asp
It contains historical and current statistics on W3Schools visitors.
That will give you a better idea. Obviously the number is highly different for technology related sites. Example: I remember a popular tech blog mentioning that their firefox users were over 50%. So it really depends on your audience as well.
Hope that helps.
Then again, we also get about 15% of our traffic from Mac users -- we love our Macs here in LA!
So if you cut out most of the Mac users, it looks pretty close to the percentages iamyoohoo cited.
no matter what your going to need to support it
depends of the content of the site, thus the user type.