A firm's stock generated annual returns of 6%, -14%, and 16% in Years 1 through 3, respectively. What was the standard deviation of the stock's returns during the 3-year holding period? (Round your answer to the nearest one-hundredth of a percent. Do not enter the percentage symbol. For example, if your answer is 12.3456789%, enter 12.35. Do not worry if Canvas truncates trailing zeros.)