You invest $1000 in a mutual fund. You expect that the fund will earn a 8% return annually before expenses (~this is how much the fund's assets go up). You have a choice between purchasing class A mutual fund shares with a front-end load of 4% and no expenses or class C mutual fund shares with no loads but a 1% 12b-1 fee. What is your investment horizon if you are indifferent between these two? (Round to the nearest whole number of years.)