Ask HN: What % of Open Source commits are from outside devs for consumer apps?

I have a theory that most Open Source contributions come from corporations like IBM, Google, and Redhat where their primary revenue stream is support or search or ads. The reason we don't see many poplar end-user apps being Open Source is that there's no economic model behind them. Firefox is the best example but their funding primarily comes from Google. I also suspect that the vast majority of their commits are from developers paid for by Mozilla. I think the argument that if you just Open Source your app that you will get commits from the developer community is fallacious. I'd like to have real numbers to back it up though.