An effective interest rate for a calendar year is the interest earned in
that year divided by the average level of assets held during the year. This rate reflects
the entire portfolio of securites held by the Social Security trust funds
(OASI and DI).
Effective rates for the trust funds on a combined basis are shown below; rates for
each trust fund, separately, are also available.
Average annual special-issue interest rates and effective
annual interest rates (percent)