Green Mountain Power Company obtained authorization to issue 20-year bonds with a face value of $10 million. The bonds are dated May 1, 2021, and have a contract rate of interest of 10 percent. They pay interest on November 1 and May 1. The bonds were issued on August 1, 2021, at 100 plus three months accrued interest. What was the prevailing market rate of interest on the date that the bonds were issued?