Year Percent 1960-01-01 36.12470000000000 1961-01-01 36.08860000000000 1962-01-01 35.04090000000000 1963-01-01 34.84080000000000 1964-01-01 35.20790000000000 1965-01-01 35.10870000000000 1966-01-01 37.76970000000000 1967-01-01 42.38720000000000 1968-01-01 44.34380000000000 1969-01-01 44.79500000000000 1970-01-01 45.82090000000000 1971-01-01 45.97500000000000 1972-01-01 46.21500000000000 1973-01-01 46.54500000000000 1974-01-01 46.72670000000000 1975-01-01 48.50760000000000 1976-01-01 49.38550000000000 1977-01-01 52.11980000000000 1978-01-01 54.32670000000000 1979-01-01 55.75190000000000 1980-01-01 56.84710000000000 1981-01-01 60.68670000000000 1982-01-01 67.39930000000000 1983-01-01 64.11360000000000 1984-01-01 61.45040000000000 1985-01-01 60.84380000000000 1986-01-01 62.28080000000000 1987-01-01 62.06040000000000 1988-01-01 62.78700000000000 1989-01-01 66.46620000000000 1990-01-01 70.80400000000000 1991-01-01 75.26110000000000 1992-01-01 76.20210000000000 1993-01-01 76.23330000000000 1994-01-01 73.65850000000000 1995-01-01 74.23620000000000 1996-01-01 74.64600000000000 1997-01-01 73.88000000000000 1998-01-01 73.74040000000000 1999-01-01 71.40830000000000 2000-01-01 68.76190000000000 2001-01-01 99.21050000000000 2002-01-01 126.01899999999999 2003-01-01 121.70000000000000 2004-01-01 118.60400000000000 2005-01-01 120.30600000000000 2006-01-01 126.41900000000000 2007-01-01 119.82799999999999 2008-01-01 115.60500000000000