The risk-free rate of return is 1% and the expected return on the market portfolio is 9.8%. Oklahoma Oilco has a beta of 1.64 and a standard deviation of returns of 17.4%. Oilco's marginal tax rate is 21%. Analysts expect Oilco's net income to grow by 5% per year in the foreseeable future. Floatation costs of issuing new common stock are 3.4%. Using the capital asset pricing model, what is Oklahoma Oilco's cost of retained earnings, in %? Drop the % symbol. E.g., if your answer is 10.23%, record it as 10.23.