Assume these are the stock market and Treasury bill returns for a 5-year period Stock Market T-Bill Return Return (%) Year 2011 2012 2013 2014 2015 -34.43 31.60 14.66 3.28 19.36 4.00 0.40 0.26 0.03 0.05 a. What was the risk premium on common stock in each year? (Do not round intermediate calculations. Enter your answers as a percent rounded to 2 decimal places.) Year Risk Premium 2011 2012 2013 2014 2015 b. What was the average risk premium? (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.) Average risk premium c. What was the standard deviation of the risk premium? (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.) Standard deviation