Assume these are the stock market and Treasury bill returns for a 5-year period:

Year	Stock Market Return (%)	T-Bill Return (%)
2016	33.30	0.12
2017	13.20	0.12
2018	3.50	0.12
2019	14.50	0.07
2020	23.80	0.09

Required:

What was the risk premium on common stock in each year?

What was the average risk premium?

What was the standard deviation of the risk premium? (Ignore that the estimation is from a sample of data.)