What about this model: Say programming skill is more or less proportional to the time spent programming. Further say that at any moment a person has a certain p

What about this model: Say programming skill is more or less proportional to the time spent programming. Further say that at any moment a person has a certain probability of leaving the industry. In that case the skill curve over the population should be a geometric, hockeystick like curve. It wouldn't make sense that the majority of people had experience in the 5-8 years interval say.