You conflate two sets of different statistics.......I'll accept your premise that as a ratio of population the US incarcerates more of its citizens than any other country.

But the execution rates are a different set of figures:

In terms of numbers that we know of, here are the top 6:

1) China

2) Iran (though it is No.1 in ratio to it's population size)

3) Iraq

4) USA

5) Pakistan

6) Saudi Arabia

http://www.ibtimes.com/articles/217756/20110921/troy-davis-execution-united-states-execution-rate.htm

 

And yes, I agree that the execution of Troy Davis was a disgrace. Hopefully it will encourage some States to outlaw the death penalty but unfortunatly I doubt it will be enforced nationwide.