How Often Do People Who Commit Murder Turn Themselves In?

I was watching a History Channel program about famous crimes/mass murderers and I got to thinking - how often do people who commit murder actually turn themselves in? I’m sure it’s a small number of people, but then it got me to thinking - is their something inherent in human nature for to to cover up one’s mistakes, even the really egregious ones (like murder)? Or is based more on someone’s individual personality (e.g. those with a high moral sense or sense of guilt would be more likely to turn themselves in or confess their crime than the average person)?

I don’t know about the overall statistics, but after my uncle shot and killed a man he turned himself in to the police pretty much immediately. From what I know, it was a heat of the moment thing (there was a fight over a woman they were both involved with, I was only about 9 at the time so I’m a bit vague on the details) and I would suspect that someone in that situation might be more likely to be horrified at what they had done and turn themselves in than if it was premeditated, but that’s just my guess. I’m sure there will be others coming along shortly with actual numbers.