Assume these are the stock market and Treasury bill returns for a 5-year period: Year 2011 2012 2013 2014 2015 Stock Market T-Bill Return Return (%) (%) -37.03 1.80 28.60 0.30 16.86 0.14 1.28 0.06 16.36 0.08 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 2011 2012 Risk Premium (39.10) % 28.30% 16.721% 1.22 % 16.28 % 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 4.98%) 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