Year	Percent
1974-01-01	1.3310100000000000
1975-01-01	2.5988900000000004
1976-01-01	4.0147400000000000
1977-01-01	5.2238000000000000
1978-01-01	6.0544199999999995
1979-01-01	6.1473300000000000
1980-01-01	5.4796100000000000
1981-01-01	4.8025000000000000
1982-01-01	2.9145500000000000
1983-01-01	4.0028700000000000
1984-01-01	4.0019599999999995
1985-01-01	3.8527000000000000
1986-01-01	3.8037600000000000
1987-01-01	3.8546600000000000
1988-01-01	4.3892600000000000
1989-01-01	6.0798000000000000
1990-01-01	5.1556700000000000
1991-01-01	5.9388000000000000
1992-01-01	8.0402100000000000
1993-01-01	4.7874800000000000
1994-01-01	5.5993600000000000
1995-01-01	4.5598800000000010
1996-01-01	3.5965199999999995
1997-01-01	3.0907000000000000
1998-01-01	3.6323900000000000
1999-01-01	2.7893200000000000
2000-01-01	3.3342400000000003
2001-01-01	3.0964500000000000
2002-01-01	2.4799000000000000
2003-01-01	1.4154100000000000
2004-01-01	1.3934500000000000
2005-01-01	3.0576600000000000
2006-01-01	3.8017400000000000
2007-01-01	4.0283800000000000
2008-01-01	2.9024500000000000
2009-01-01	1.7746500000000000
2010-01-01	2.0004100000000000
2011-01-01	2.2006500000000000
2012-01-01	2.5485900000000004
2013-01-01	2.7161800000000000
2014-01-01	3.1342400000000000
2015-01-01	2.5845300000000000
2016-01-01	2.5842200000000000
2017-01-01	2.8716300000000000