I found that Jelly Bean is still taking a fair amount of installed devices.
If I plan to make an application for Jelly Bean, do I have to set source code compatibility 1.6?
Jellybean is 4.1-4.3 If you are looking at that api 16 that's different than android version 1.6
At this point, it looks like anything under 2.2 (froyo) is on less than 0.2% of android devices.
In this graphic you can see a distribution of Android platform versions used by Android smartphone owners in October 2015. The figures are based on the number of Android devices that have accessed the Google Play Store within a 7-day period ending on October 5th, 2015.
This graph shows the most common SDK installed on Android phones and tablets used by AppBrain SDK users as of December 8, 2015.
So I'd suggest anything 4.0.x and up will suffice for making most of the public happy with your apps.