Assume these are the stock market and Treasury bill returns for a 5-year period: Year 2011 2012 2013 2014 2015 Stock Market Return (%) 0.98 16.06 33.06 12.71 0.67 T-Bill Return (%) 0.03 0.05 0.07 0.05 0.21 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.) Risk Premium 0.98 % Year 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? (Ignore that the estimation is from a sample of data.) (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.) Standard deviation