Suppose we have the following returns for large-company stocks and Treasury bills over a six-year period:

Year	Large Company			US Treasury Bill
1		3.96			4.50
2		14.12			4.88
3		19.01			3.80
4		14.67			6.96
5		32.16			4.88
6		37.26			6.14
c-2 Calculate the observed risk premium in each year for the large-company stocks versus the T-bills. What was the standard deviation of the risk premium over this period? (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Standard deviation %