@Linkat,
I typically weed through about 40 resumes in order to get 10 people worth calling. Then phone conversations allow me to eliminate 8 of the 10 and I interview the 2 remaining. Out of those 2, I have a 50% chance of finding someone I consider a viable new-hire.
When I was in High-Tech, we used to do internship programs for programmers in college to get them extra credit for their courses. Typically, in every group of 10 individuals, 8 students would be completely clueless about what they were trying to do. They would spend weeks complaining about how they had to re-install their OS because it crashed. That was the "dog ate my homework" excuse of the early 2000's. It sounded like they were actually doing something technical, when in fact they just didn't know ****.
I think the natural ratio of people who don't know ****, to people who do, is about 10 to 1. I don't know why, but in a random sampling, I think that's about what you get.
How many people does Jay Leno have to stop on a street corner and ask simple questions before he gets someone who has a clue? All we ever see are the ones who fail, because it makes better TV, but I bet it's around 10 to 1.