What is the annual interest rate for long-term corporate bonds, if the real interest rate is 2.1% per year, the inflation premium is 2.7% per year, the liquidity premium is 0.6% per year, the maturity premium is 0.8% per year, and the default premium is 3.1% per year? 1) 9.3% 2) 6.7% 3) 7.5% 4) 9.1% 5) 8.7%