In addition, Treasury published daily linear extrapolation factors that could be added to the Long-Term Average Rate to allow interested parties to compute an estimated 30-year rate. On June 1, 2004, Treasury discontinued the "LT>25" average due to a dearth of eligible bonds. As a result, there are no 20-year rates available for the time period January 1, 1987 through September 30, 1993. Treasury Yield Curve Rates: These rates are commonly referred to as "Constant Maturity Treasury" rates, or CMTs. Yields are interpolated by the Treasury from the daily yield curve.