The historical stock returns for TechFluent, Inc. are shown below: Year 1 2 3 4 Return 18% 10% -16% 4% What is the standard deviation of returns for TechFluent, Inc. stock over this 4-year period. (Compute the standard deviation assuming this is a population of returns, not a sample that is, use the procedure described in the textbook for calculating the standard deviation of a series of stock returns). Record your answer as a percent, rounded to two decimal places, but do not include a percent sign in your answer.