Year	Percent
1964-01-01	3.9406800000000004
1965-01-01	3.4760100000000000
1966-01-01	3.7768200000000000
1967-01-01	4.0909000000000000
1968-01-01	5.1559800000000005
1969-01-01	5.5152900000000000
1970-01-01	5.9681400000000000
1971-01-01	5.7752000000000000
1972-01-01	6.2259300000000000
1973-01-01	7.2100000000000000
1974-01-01	9.5032600000000010
1975-01-01	11.7147000000000000
1976-01-01	9.6348200000000000
1977-01-01	9.0611400000000000
1978-01-01	9.2104800000000000
1979-01-01	8.4880000000000000
1980-01-01	8.0871500000000000
1981-01-01	7.6899200000000000
1982-01-01	6.9319000000000000
1983-01-01	6.5463300000000000
1984-01-01	5.9116200000000000
1985-01-01	5.9569700000000000
1986-01-01	6.1596900000000000
1987-01-01	6.1666800000000000
1988-01-01	18.4721000000000000
1989-01-01	30.9785000000000000
1990-01-01	32.7163000000000000
1991-01-01	36.2917000000000000
1992-01-01	36.7091000000000000
1993-01-01	39.9204000000000000
1994-01-01	40.7771000000000000
1995-01-01	40.3386000000000000
1996-01-01	44.2612000000000000
1997-01-01	46.9498000000000000
1998-01-01	47.1440000000000000
1999-01-01	48.3604000000000000
2000-01-01	48.4396000000000000
2001-01-01	46.5402000000000000
2002-01-01	43.6324000000000000
2003-01-01	40.9444000000000000
2004-01-01	41.7202000000000000
2005-01-01	42.9106000000000000
2006-01-01	44.2348000000000000
2007-01-01	46.1993000000000000