If we take robinrob's point, and measure only "people who have programmed", then I would still expect a very positively skewed distribution. There are really a

If we take robinrob's point, and measure only "people who have programmed", then I would still expect a very positively skewed distribution. There are really a lot of people in the "I tried it and didn't like it" category. For almost any boundary you choose, a majority of people will sneak in just over that boundary, leaving a long one-sided tail. This skewed distribution would appear even if you cut a Normal distribution. A Normal distribution occurs when everyone is expected to be at the same average level but could move up and down equally due to many random factors. When learning skills, people generally start at a 0 level and generally move up. That won't be Normal. If you take a cohort of programmers with exactly the same experiences, that could plausibly follow a Normal distribution of skill. If you take e.g. all professional programmers, that won't.