Google started to roll out their latest OS upgrade last month called Marshmallow. There are only a handful of devices that support it at the moment, including past and present Nexus smartphones. According to Android’s Platform Distribution rates for the month of November, Marshmallow is running on a mere 0.3% of “active” devices. The data is collected from signals sent to the Play Store, which helps identify what Android version is on handsets or tablets.
Marshmallow might not be embraced by smartphone companies yet, but older versions of Android seem to be far more popular. Lollipop (5.0 and 5.1) accounts for 26% percent, while Kit Kat (4.4) is the most popular version with 38% market share.
I bet Google right now wished they could see the type of OS upgrade metrics that Apple enjoys. Within 1 month of iOS 9 coming out, over 66% of iPhone users had it installed.