The original Android Jelly Bean build (4.1) was released in mid-2012, and now this Android version is the biggest mount of all Android versions, according to Android Developers Dashboard page.
As you can see from the picture above (Click the picture to enlarge), the Android 4.1 Jelly Bean is powering 35.9% Android devices. The same Jelly Bean name but on the different version (4.2) is powering 15.4% Androids, and the Jelly Bean 4.3 powers the 7.8% of Android devices.
This means that Jelly Bean versions are the most used Android devices to date (growing from 54.5% in December to 59.1% in January).
Other versions included are Android Gingerbread (21.2%), Ice Cream Sandwich (16.9%), KitKat, which is the latest Android build (1.4%), Froyo (1.3%), and Honeycomb (0.1%).
The research starts from 1st January 2014 and ends 7 days later.