Here are stock market and Treasury bill percentage returns between 2006 and 2010:

Year	Stock Market Return	T-Bill Return
2006	18.37	7.10
2007	8.71	6.76
2008	39.53	2.50
2009	30.40	0.90
2010	20.36	1.02

a.	What was the risk premium on common stock in each year? (Negative values should be indicated by a minus sign. Round your answers to 2 decimal places.)

Year	Risk Premium
2006	%
2007	%
2008	%
2009	%
2010	%

b.	What was the average risk premium? (Do not round intermediate calculations. Round your answer to 2 decimal places.)

Average risk premium

%

c.	What was the standard deviation of the risk premium? (Do not round intermediate calculations. Round your answer to 2 decimal places.)

Standard deviation of the risk premium

%