Right on schedule, the Android Developers Dashboard has reported the share of devices running each version of Android as of February 4, 2013. These numbers are measured based on the number of users accessing Google Play within a 14 day period, which is a great indication of devices being actively used. As you can see in the chart above, Android 4.0 and higher is nearing the 50-percent mark, at 42.6-percent currently. Gingerbread is still holding down the top spot at 45.6-percent, but we're nearing the point where device running Gingerbread will be overtaken by versions with the new design language.
As you'll see in the graph after the break, the share of Gingerbread devices is slowly but surely decreasing, making way for a notably quick Jelly Bean advancement. Jelly Bean (both 4.1 and 4.2) total up to 13.6-percent of devices, surely helped by the success of the Nexus 7 and notable updates to popular devices like the Galaxy S3.
Source: Android Developers Dashboard