Martin and Marcy McCormack have just become proud parents of septuplets. They have savings of $5000. They want to invest their savings so that they can partially support the children's university education. Martin and Marcy hope to provide $20,000 for each child by the time the children turn 18 . What must the annual rate of return on the investment be for Martin and Marcy to meet their goal? The annual rate of return on the investment would need to be at least %. (Round to two decimal places.)