Year	Percent
1961-01-01	10.618300000000000
1962-01-01	10.919500000000000
1963-01-01	11.257100000000000
1964-01-01	11.814800000000000
1965-01-01	13.451500000000000
1966-01-01	13.516100000000000
1967-01-01	13.335200000000000
1968-01-01	13.322900000000000
1969-01-01	13.966600000000000
1970-01-01	8.073670000000000
1971-01-01	7.942000000000000
1972-01-01	8.422369999999999
1973-01-01	10.178700000000000
1974-01-01	11.144900000000000
1975-01-01	12.201200000000000
1976-01-01	13.245600000000000
1977-01-01	12.866100000000000
1978-01-01	14.031600000000000
1979-01-01	15.337900000000000
1980-01-01	15.768500000000000
1981-01-01	16.256200000000000
1982-01-01	16.779300000000000
1983-01-01	16.867800000000000
1984-01-01	20.062000000000000
1985-01-01	20.989500000000000
1986-01-01	21.203500000000000
1987-01-01	21.275000000000000
1988-01-01	22.741600000000000
1989-01-01	24.527600000000000
1990-01-01	25.694900000000000
1991-01-01	31.139100000000000
1992-01-01	31.318800000000000
1993-01-01	26.681200000000000
1994-01-01	29.284000000000002
1995-01-01	28.396600000000000
1996-01-01	26.284800000000000
1997-01-01	29.465100000000000
1998-01-01	34.011800000000000
1999-01-01	35.425200000000000
2000-01-01	35.512900000000000
2001-01-01	36.752200000000000
2002-01-01	41.255100000000000
2003-01-01	44.969400000000000
2004-01-01	42.775300000000000
2005-01-01	41.848900000000000
2006-01-01	39.776400000000000
2007-01-01	36.438900000000000
2008-01-01	34.732200000000000