The way contribution rate is calculated is documented in the about page (http://www.krihelinator.xyz/about). I hope that it answers your question.
In general, it seems that just from reading the term "contribution rate" several people predict that it only count commits. Commits have the least weight in the calculation. The number of contributors are much more important as well as number of issues and pull requests.
In general, it seems that just from reading the term "contribution rate" several people predict that it only count commits. Commits have the least weight in the calculation. The number of contributors are much more important as well as number of issues and pull requests.