You have collected the following annual returns data for Stock A and Stock B: A B 2014 8% 11% 2015 9% 10% 2016 5% 12% 2017 4% 7% 2018 13% 9% 2019 7% 8% Suppose you have held a portfolio comprised of 60% in Stock A and 40% in Stock B for these six years. What is the standard deviation of returns on your portfolio? Enter your answer in units of percent (not a decimal), round it to one decimal place, and omit any percent signs (i.e., enter 20.91% as 20.9)