You have discovered that when the required rate of return on a bond you own fell by 0.5 percent from 9.7 percent to 9.2 percent, the fair present value rose from $945 to $970. The bond pays interest annually. What is the duration of this bond? Assume annual payments. (Do not round intermediate calculations. Round your answer to 1 decimal place. (e.g., 32.1)) Duration of this bond years