Year	Percent
1970-01-01	0.35412400000000000
1971-01-01	0.46155300000000000
1972-01-01	0.48516800000000004
1973-01-01	0.51804600000000000
1974-01-01	0.40397900000000000
1975-01-01	0.33823900000000000
1976-01-01	0.30514200000000000
1977-01-01	0.31973400000000000
1978-01-01	0.29021600000000000
1979-01-01	0.31050500000000003
1980-01-01	0.31368900000000000
1981-01-01	0.34329400000000000
1982-01-01	0.41942399999999996
1983-01-01	0.37430399999999997
1984-01-01	0.34692300000000000
1985-01-01	0.35316600000000000
1986-01-01	0.31568700000000000
1987-01-01	0.31138899999999997
1988-01-01	0.31488200000000000
1989-01-01	0.30142500000000000
1990-01-01	0.22558499999999998
1991-01-01	0.20796700000000000
1992-01-01	0.22111199999999998
1993-01-01	0.25832000000000000
1994-01-01	0.26291300000000000
1995-01-01	0.14891000000000000
1996-01-01	0.15640800000000000
1997-01-01	0.16045700000000000
1998-01-01	0.14593100000000000
1999-01-01	0.10987400000000000
2000-01-01	0.10315200000000000
2001-01-01	0.11314000000000000
2002-01-01	0.10392799999999999
2003-01-01	0.19576900000000000
2004-01-01	0.19942500000000000
2005-01-01	0.18559700000000000
2006-01-01	0.21357700000000000
2007-01-01	0.19423600000000000
2008-01-01	0.17614300000000000
2009-01-01	0.19952300000000000
2010-01-01	0.20569800000000000
2011-01-01	0.20001000000000000
2012-01-01	0.19792900000000000
2013-01-01	0.18676600000000002
2014-01-01	0.16850400000000000
2015-01-01	0.17303900000000000
2016-01-01	0.17174300000000000
2017-01-01	0.17595800000000000