Year	Percent
1974-01-01	5.1867100000000000
1975-01-01	5.5481000000000000
1976-01-01	5.5967500000000000
1977-01-01	5.5348700000000000
1978-01-01	6.6008200000000000
1979-01-01	7.3842000000000000
1980-01-01	8.9853700000000000
1981-01-01	10.1342000000000000
1982-01-01	12.0305000000000000
1983-01-01	13.8073000000000000
1984-01-01	16.0381000000000000
1985-01-01	14.5296000000000000
1986-01-01	13.7094000000000000
1987-01-01	13.4083000000000000
1988-01-01	13.2764000000000000
1989-01-01	13.8962000000000000
1990-01-01	14.8378000000000000
1991-01-01	15.8379000000000000
1992-01-01	15.9002000000000000
1993-01-01	15.7750000000000000
1994-01-01	15.9029000000000000
1995-01-01	12.4731000000000000
1996-01-01	7.0355200000000000
1997-01-01	5.3125700000000000
1998-01-01	4.3504400000000000
1999-01-01	3.9125900000000002
2000-01-01	3.5775300000000003
2001-01-01	3.0697600000000000
2002-01-01	2.6942800000000000
2003-01-01	2.5764299999999998
2004-01-01	2.2642800000000000
2005-01-01	2.0209900000000003
2006-01-01	1.7969099999999998
2007-01-01	1.5933300000000000