The stock return for GM over the past 5 years has been 9%, 12%, -14%, 1%, and -9%. What is the (arithmeticx) average return for GM?

Using 25 years of data, you estimate the arithmetic average return for a certain stock to be 5.9% and the geometric average return to be 4.7%. Using Blume's formula, what is your average forecasted return over a 6 year period?