I learned that only 36% of astronauts have earned doctorate degrees, but most of the astronauts selected with only a masters or bachelors had extensive NASA and/or military experience. The typical astronaut has one bachelors and one masters degree, although some do have more than one of either type of degree, with the most being 2 bachelors and 3 masters. Some other tidbits of note are that 4 astronauts have MBAs, 1 has a DVM, and only 1 has a MD/Ph.D.
I suspect the percentage of astronauts with military experience would go up if I included the larger pool or former astronauts too, since in the pre-shuttle era, nearly all astronauts were military. However, the current pool has a 60/40 split, meaning it's still beneficial to have a military background, but it's not a must.
I think the four histogram plots are really interesting because they address the age of astronauts when they're selected compared to the age when they actually get to fly into space. Most astronauts are selected when they're in their 30s and get to fly several years later. Some astronauts have been eligible for flight assignment for over a decade but have still not been assigned. A few of them have risen to management positions and might never get to fly. I can see why someone like Peter Diamandis would get disillusioned with the NASA astronaut program and strike out on his own to spark the personal spaceflight revolution. After all, the chances of getting selected are very slim, and even if you are selected, you might not even get to go into space. If you do, you might have to wait several years and will only get go up a few times at best during your spaceflight career. Note that the last plot of number of days in space would be a lot different if I included cosmonauts too, since they have much more long duration spaceflight experience.