I'm glad that helped. Yes, you can get the headline answer online, but for something like this it's really hard to put together a proper view of how the relationship fits together. And, while a lot of Ubuntu (though not all) is driven by a company which can have a sort of official view of things, Debian is an association of several hundred developers and expecting a unified opinion on just about anything is thus hopeless.

I'd love to have a version of that timeline scaled by log(number of developers) or something so that it's easier to see the large-scale structure. Number of users would be even better but of course nobody really has any way to measure that short of terrible proxy metrics.