What percentage of people in jail are innocent of their convicted crimes?

[I spent the winter writing songs about getting better]

I guess when I posted that I was thinking of the death penalty.  I always get disgusted whenever someone is let off of Death Row because DNA evidence proves them innocent all along.  It makes you wonder what was going on before DNA evidence (a systemic flaw). 

It turns my stomach to think about.  It's one thing to die tragically on the side of the road or at the hands of a bad guy or disease, but to die tragically at the hands of the state when you are innocent of the accusations is abominable.  History is full of such cases and everyone of them is horrible.  Thank God for DNA.

That's one of the reasons why I'm against the death penalty and am so glad my state doesn't kill people.