Year	Percent
1970-01-01	1.6897799999999998
1971-01-01	0.8701390000000000
1972-01-01	1.2076700000000000
1973-01-01	1.0235900000000000
1974-01-01	0.9160510000000001
1975-01-01	0.7779290000000000
1976-01-01	2.8344400000000003
1977-01-01	2.6945099999999997
1978-01-01	2.7563700000000000
1979-01-01	2.9333700000000000
1980-01-01	2.7612700000000000
1981-01-01	2.5168600000000000
1982-01-01	2.3857400000000000
1983-01-01	2.2616600000000000
1984-01-01	1.9844300000000000
1985-01-01	4.7972199999999990
1986-01-01	3.6816800000000005
1987-01-01	4.6868099999999995
1988-01-01	5.3737100000000000
1989-01-01	4.4940700000000000
1990-01-01	4.4503000000000000
1991-01-01	3.3849300000000000
1992-01-01	3.0520600000000000
1993-01-01	5.7954099999999995
1994-01-01	5.4384000000000000
1995-01-01	5.0558200000000000
1996-01-01	5.2774700000000000
1997-01-01	5.7058900000000000
1998-01-01	6.4865500000000000
1999-01-01	7.3680100000000010
2000-01-01	7.5654900000000000
2001-01-01	7.7416100000000005
2002-01-01	8.0192600000000010
2003-01-01	10.7444000000000000
2004-01-01	11.0221000000000000
2005-01-01	7.5284400000000000
2006-01-01	8.0117800000000000
2007-01-01	7.6908000000000000
2008-01-01	7.4665100000000000
2009-01-01	7.0585800000000000
2010-01-01	7.2004300000000000
2011-01-01	7.3354300000000010
2012-01-01	7.0264700000000000
2013-01-01	7.1582700000000000
2014-01-01	7.2813100000000000
2015-01-01	7.5523899999999990
2016-01-01	7.6142900000000000
2017-01-01	8.1360000000000010