Latest data shows 36.1% of Android devices running Lollipop with just 2.3% sporting Marshmallow
22.3% of Android devices were powered by Android 4.1 through Android 4.3, known as JellyBean. The 2.3% share held by Android 4.0.3-4.0.4 Ice Cream Sandwich was topped by the 2.6% slice of the pie that belonged to Android 2.3.3-2.3.7 Gingerbread.
Once the next generation flagship models from HTC, LG and others start to join the Samsung Galaxy S7 and Samsung Galaxy S7 edge, we should see a pick up in devices carrying Android 6.0. At the same time, older models currently running Android 5.0 and Android 5.1 will start receiving their update to Marshmallow. It might be July or August before we see a measurable increase in Android 6.0 powered Android devices.
source: Android via MobileSyrup