According to data from market research company StartCounter, by May 2012, Chrome has overtakes IE as the No. 1 web browser globally. Firefox and Safari is following IE to be 3rd and 4th most popular web browser.

In May, market share of Chrome is 33%, while IE only gets 32%. Firefox is slowly dropping, which has a share of 25%. 

However, with release date of Windows 8 approaching, IE 10 will also be shipped with Win8, at that time, the number of users who use IE may increase because according to some testings, IE10's performance is satisfying and it also has relative good HTML5 support. However for Firefox, it may get in trouble if it cannot provide users some new and useful features.

For more information about the market share of all web browsers, please visit : http://gs.statcounter.com/

Reference : http://tech.sina.com.cn/i/2012-05-21/15157141465.shtml