This misses a couple of factors. a) Not every one is based in US, so they charge viewing their currency rate diff. Hence 15k USD per annum might be a good incom

This misses a couple of factors. a) Not every one is based in US, so they charge viewing their currency rate diff. Hence 15k USD per annum might be a good income for some one in a remote country. b) Not every one is a full time free lancer. For instance i only work free lance, when i have time, got a really interesting project or am in need of money apart from a full time day job. Some times i have like 15 hours worked in six months, some times more. I don't see any way to even point out those things here. Won't these drastically impact the data? P.S. yes - another missed factor is years of experience - No? If you get mostly people right out of college (or even in college for that matter) making similar to those on full time jobs after many years, that is an interesting one too. No?