Year	Percent
1975-01-01	0.2258500000000000
1976-01-01	0.3608060000000000
1977-01-01	0.4503080000000000
1978-01-01	1.4280400000000000
1979-01-01	1.7852100000000000
1980-01-01	3.7693100000000000
1981-01-01	5.1985400000000000
1982-01-01	6.0667000000000000
1983-01-01	5.6981800000000010
1984-01-01	4.9796700000000000
1985-01-01	4.8783800000000000
1986-01-01	5.0891000000000000
1987-01-01	5.2404800000000010
1988-01-01	5.1253600000000000
1989-01-01	5.1237800000000000
1990-01-01	4.9894000000000000
1991-01-01	4.9119600000000000
1992-01-01	5.6457200000000000
1993-01-01	6.1078000000000000
1994-01-01	6.1035699999999995
1995-01-01	6.1472600000000000
1996-01-01	6.0669800000000000
1997-01-01	6.1869600000000000
1998-01-01	6.4295000000000000
1999-01-01	6.7738400000000000
2000-01-01	6.9552500000000000
2001-01-01	7.4274800000000000
2002-01-01	7.8376199999999990
2003-01-01	7.5388600000000010
2004-01-01	7.6165899999999995
2005-01-01	8.0945400000000000
2006-01-01	7.6652600000000010
2007-01-01	7.7502600000000010
2008-01-01	7.1828100000000010
2009-01-01	7.9316900000000000
2010-01-01	7.2682400000000000
2011-01-01	7.8925100000000010
2012-01-01	8.7666300000000010
2013-01-01	8.6442600000000010
2014-01-01	8.8664200000000000
2015-01-01	8.6894000000000000
2016-01-01	8.8788300000000000
2017-01-01	8.2481500000000000