during the last week of every month Google conducts a survey to find out the install base the various versions of Android OS and track their growth and decline. The last month Android 4.x install base was about 25% of all Android OS. the most recent reports from Android developers says that the figure has shown a good relocation towards the adoption of the most recent version of the OS and now it has grown to 30% install base, 28.5% to be exact.

The recent rise in Android 4.x spread has been fired by the Ice cream Sandwich and Jelly Bean updates rolled out by device manufacturers and the grow in the sale of phones with Android OS. Android 2.3 Gingerbread is still a clear winner with about 54% share. It has been much more than a year because Google introduced the Android 4.x version but the company does not seem to be sincere about pushing the OS updates to many Android phones.

Source: Android Developers