And that's why I believe that requesting a mandatory CLA should drive contributions down in OSS projects. Otherwise, you're basically providing free labor without the counterpart's promise of keeping the code free, which is (should?) be the reason one is making their contributions to start with.

I also don't believe they receive many non-employee contributions (probably because the software is more advanced than most open source projects). You can get a breakdown of their contributions at:

https://imgur.com/a/UCJ6y9r

The interesting one is he second image which filters by code contributors that have contributed more than 500 lines of code churn.

Note, I'm not taking into consideration if code contributions were merged or not, just that somebody created a pull request/commit.