The count of contributions (summary of Pull Requests, opened issues and commits) to public repos at GitHub.com from Thu, 03 Apr 2014 02:35:55 GMT till Fri, 03 Apr 2015 02:35:55 GMT.
Only first 1000 GitHub users according to the count of followers are taken. This is because of limitations of GitHub search. Sorting algo in pseudocode:
githubUsers .filter((user) -> user.followers > 386)