Actually it's about six times the international median rate. The USA has a prison population of about 751 per 100,000 citizens. The median rate for the rest of the world is 125. The UK, for example, is 151. None of this is really relevant in this topic.
Some details here:
http://www.nytimes.com/2008/04/23/wo...pagewanted=all
However, I have to say I was another one to be shocked that the pilot in question is facing criminal charges rather than getting medical/mental help.