KitKat remains the most used Android iteration, powering 35.5% of devices, down from 36.1% last month. Lollipop is installed on 34.1% of devices, while Jelly Bean (which, mind you, was first released in 2012) can still be found on 23.9% of devices.
We can't say we're surprised by the small percentage of Marshmallow devices currently in use, because new versions of Android have always taken their sweet time to reach a significant number of phones and tablets. Still, we're certainly not thrilled with the way that manufacturers are handling Android updates.
The data discussed in this article was gathered in a 7-day period ending on February 1. Hopefully, by next month, Marshmallow will arrive on at least another 1 percent of all Android devices.
source: Android Developers