Yields on short-term bonds tend to be more volatile than yields on long-term bonds. Suppose that you have estimated that the yield on 20 -year bonds changes by 12 basis points for every 18.9-basis-point move in the yield on 5 -year bonds. You hold a $4.5 million portfolio of 5 -year maturity bonds with modified duration 4 years and desire to hedge your interest rate exposure with T-bond futures, which currently have modified duration 9 years and sell at F0=$75. How many futures contracts should you sell? (Do not round intermediate calculations. Round your final answer to the nearest whole number.)