historical return for the S&P

Anybody know the average historical return for the S&P 500 index for the last 60+ years. I have heard 10% and 12%. Anybody know which one is correct?

thanks

 

with or without dividends

 

what period exactly?

12% over the last 60 years
10% over the last 80 years

but what you should be concerned about ... how about the next 10 years?