Heh I can use that site to back out average interest rates for each year.
1980-1981: 13.5%
1981-1982: 10.3%
1982-1983: 6.2%
1983-1984: 3.2%
1984-1985: 4.3%
1985-1986: 3.6%
1986-1987: 1.9%
1987-1988: 3.6%
1988-1989: 4.1%
1989-1990: 4.8%
1990-1991: 5.4%
1991-1992: 4.2%
1992-1993: 3.0%
1993-1994: 3.0%
1994-1995: 2.6%
1995-1996: 2.5%
1996-1997: 3.0%
1997-1998: 1.7%
1998-1999: 1.6%
1999-2000: 2.7%
2000-2001: 3.4%
2001-2002: 1.6%
2002-2003: 2.4%
2003-2004: 1.9%
2004-2005: 3.3%
2005-2006: 3.4%
Interesting, coulda sworn it was closer to 4% but it's been a lot lower the last 15 years or so. Early 80's are crazy too hehe.