And this is the best-case scenario. The CBO alternative projects an average interest rate of 4.6 percent from 2010 to 2084, with lower rates in the near future due to the recession. Interest rates in 2010 are estimated at 2.26 percent, slowly increasing through 2030 and leveling off at about 4.9 percent. These projected rates are historically low for the United States. What’s more, these interest rates assume that investors look at these spending projections and don’t change their perceptions of the country’s solvency.