Year	Percent
1971-01-01	5.6488100000000000
1972-01-01	4.7388699999999995
1973-01-01	4.3122800000000000
1974-01-01	4.4789300000000000
1975-01-01	5.2747500000000000
1976-01-01	6.3085600000000000
1977-01-01	7.1190700000000000
1978-01-01	6.5121400000000005
1979-01-01	4.8113700000000000
1980-01-01	3.7171900000000000
1981-01-01	2.8565800000000000
1982-01-01	3.0996700000000000
1983-01-01	3.0913200000000000
1984-01-01	2.6843500000000000
1985-01-01	2.1839100000000000
1986-01-01	1.9155400000000002
1987-01-01	1.7459400000000000
1988-01-01	1.7990500000000000
1989-01-01	1.9325100000000000
1990-01-01	1.6105399999999999
1991-01-01	1.4823300000000000
1992-01-01	1.4714900000000000
1993-01-01	1.2924000000000000
1994-01-01	1.2328700000000001
1995-01-01	1.0406400000000000
1996-01-01	1.0852400000000000
1997-01-01	1.1085200000000002
1998-01-01	0.8567799999999999
1999-01-01	1.0731200000000000
2000-01-01	1.1513200000000001
2001-01-01	1.1579300000000000
2002-01-01	1.1240100000000000
2003-01-01	1.1417400000000000
2004-01-01	1.0781300000000000
2005-01-01	1.1263800000000000
2006-01-01	1.1263800000000000
2007-01-01	1.1263800000000000
2008-01-01	2.6701200000000003
2009-01-01	2.8673000000000000
2010-01-01	3.2757700000000000
2011-01-01	3.4100000000000000
2012-01-01	3.5124100000000000
2013-01-01	3.7632800000000004
2014-01-01	4.1779400000000000
2015-01-01	4.3239700000000000
2016-01-01	4.4877100000000000