You are given the following information: 8% annual coupon paid at end of year, bond issued on January 1, 1980 with face amount $1,000 maturing on December 31, 1990. The yield to maturity is 8%. Find the Macaulay duration of a bond as of January 1, 1988. What is the Macaulay duration of the bond issued on January 1, 1980.