For 3.16.0 there have been a total of 1262 changesets from 77 different developers.
Catalyst submitted 44 of those changes, and the Catalyst Academy another 13. Also Catalyst signed off (tested) 172 patches, and the Academy students signed off another 21.
I want to make a special mention of Aleisha Amohia here, who has been coming in to Catalyst every couple of weeks for a few hours after school to test patches. She has 1 patch and 8 signoffs in Koha 3.16.0