What a difference a month makes. When we last checked in early February, Gingerbread was still the most commonly used major version of Google's mobile OS despite having launched all the way back in 2010. As of the start of March, there's a different story to tell: variants of Android 4 are at last more popular, collectively representing 45.1 percent of active use versus Gingerbread's 44.2 percent. Most of those on the newer OS are still using the 2011-era Ice Cream Sandwich, although we have good news again when Jelly Bean has grown to represent 16.5 percent of current users. There's a long distance to go before any one version of Android 4 surpasses Gingerbread, but the gap is closing fast.
Source:Android Developers Dashboard