After March' 2015 revenue started decreasing and in 7th May, 2015 it was rock bottom, after developer complain google fixed the issue and it become stable like 6th May, 2016.
But it never become like March' 2015 and previous month. The revenue decrease was around 40% in May, 2015 (After google fixed the issue) in compare to March' 2015.
From June, 2015, it was consistent till Dec, 2015. And from Jan ' 2016 revenue started decreasing again and from this month April' 2016 it is further sliding.