The following table shows the prices of a sample of Treasury bonds, all of which have coupon rates of zero. Each bond makes a single payment at maturity. Years to Maturity Price (% of face value) 1 98.652% 2 95.151 3 91.344 4 87.28 What is the 1-year interest rate? What is the 2-year interest rate? What is the 3-year interest rate? What is the 4-year interest rate? Is the yield curve upward-sloping, downward-sloping, or flat? Is this the usual shape of the yield curve?