Source: Board of Governors of the Federal Reserve System (US)  

Release: H.15 Selected Interest Rates  

Units:  Percent, Not Seasonally Adjusted

Frequency:  Monthly

Yields on actively traded non-inflation-indexed issues adjusted to constant maturities. The 30-year Treasury constant maturity series was discontinued on February 18, 2002, and reintroduced on February 9, 2006.
For further information regarding treasury constant maturity data, please refer to the H.15 Statistical Release notes and the Treasury Yield Curve Methodology.

For questions on the data, please contact the data source. For questions on FRED functionality, please contact us here.