> "We estimate that 16.8 million of these people are professional developers and university-level students."

I wonder if it is relatively safe to infer from this that there are ~16.8 million developers in the world? Are there developers who never visit stackoverflow? I'd expect that number to be higher, even though 16.8M is a lot.

Also if you take all "years since learning to code" up to "9-10", they add up to 50.6%, which means that the developer population doubles every ~10 years. Though I have heard elsewhere (I think it was a talk by "uncle Bob") that the developer population doubles every 5 years, not 10.

Edit: Ha, interestingly his data was also based on stackoverflow: http://blog.cleancoder.com/uncle-bob/2014/06/20/MyLawn.html ...now does this mean the rate of growth is slowing?