Android No Longer Fragmented
apteligent.com
apteligent.com
If you exclude Jelly Bean, then excluding iOS 8, it's just 3 Android vs. 1 iOS.
I'm basing this on their charts on their pages for both Android and iOS.
The popular minSdk at the moment is 16 (4.1) . This gives a nice common API, the biggest roadbump in most cases is that you have to handle pre and post lollipop cases : with/without transitions, ripples, etc, ... It is nothing compared to having to handle 2.x devices though .. the API were pretty primitive and the hardware extremely poor.. you can't develop a 2016 app and target these devices.
Of course there are exceptions. For a camera app, the Camera2 API added in lollipop might be crucial.
In most cases, the support lib does hide most of the API differences.
Many new libs are also provided by Google directly unbundled from the SDK, such as the design lib, RecyclerView or ConstraintLayout.