Do you have any proper statistics that shows how many were innocent or proven not guilty after execution?? or it is just a presumption with "What-if-could-be-etc"?

As per my statistical analysis I found this..
1973-1983 – 22 were innocent out of 6536 = 0.003%
1984 -1993 – 30 were innocent out of 21264 = 0.001%
1994 – 2003 – 58 were innocent out of 33582 = 0.002%
2004 – Present – 29 were innocent out of 32020 = 0.001%

Scroll down to see the size of death row http://www.deathpenaltyinfo.org/death-row-inmates-state-and-size-death-r...

List of Exonerees Since 1973 http://www.deathpenaltyinfo.org/innocence-and-death-penalty#inn-yr-rc

It is just self explanatory now..