Year Percent 1980-01-01 5.00000 1981-01-01 4.50000 1982-01-01 4.50000 1983-01-01 5.00000 1984-01-01 5.00000 1985-01-01 5.00000 1986-01-01 4.64583 1987-01-01 4.22917 1988-01-01 4.81250 1989-01-01 5.50000 1990-01-01 6.50000 1991-01-01 10.64580 1992-01-01 10.27080 1993-01-01 9.70833 1994-01-01 9.41667 1995-01-01 10.50000 1996-01-01 16.54170 1997-01-01 17.00000 1998-01-01 17.00000 1999-01-01 17.00000 2000-01-01 17.00000 2001-01-01 15.66670 2002-01-01 13.00000 2003-01-01 13.00000 2004-01-01 13.00000 2005-01-01 12.75000 2006-01-01 11.00000 2007-01-01 10.75000