The count of contributions (summary of Pull Requests, opened issues and commits) to public repos at GitHub.com from Sat, 22 Dec 2012 23:34:58 GMT till Sun, 22 Dec 2013 23:34:58 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 > 229)