There are different values of "support". I "support" IE6 and 7 (I make sites for small businesses in the UK), as in, the site works, and the content is accessible. Those browsers make up 0.8% and 4.1% of the traffic last month respectively. (Why the hell is IE7 still used? How do people even have it installed???). For those, I'm happy to strip out sections if needed to get things to work, though this is rarely needed to be honest.
IE8 makes up 11.9%, so we do proper testing there, and the content should look as close as possible to modern browsers, but I'm happy to include polyfills etc where needed.
For us, Chrome is 21.1%, Mobile Safari is 17.5%, IE9 is 17.1%, and Firefox is 15.6%, so for us over 70% of users have a modern browser. These 4 are our target browsers, where everything should work.
IE8 makes up 11.9%, so we do proper testing there, and the content should look as close as possible to modern browsers, but I'm happy to include polyfills etc where needed.
For us, Chrome is 21.1%, Mobile Safari is 17.5%, IE9 is 17.1%, and Firefox is 15.6%, so for us over 70% of users have a modern browser. These 4 are our target browsers, where everything should work.