Year	Percent
1967-01-01	0.3505140000000000
1968-01-01	0.3989360000000000
1969-01-01	0.5334030000000000
1970-01-01	0.5393670000000000
1971-01-01	0.6530900000000000
1972-01-01	0.6898960000000000
1973-01-01	0.5674090000000000
1974-01-01	0.5566450000000000
1975-01-01	0.6929670000000000
1976-01-01	1.0155800000000000
1977-01-01	1.2287000000000000
1978-01-01	1.5139300000000000
1979-01-01	1.6148799999999999
1980-01-01	1.6585299999999998
1981-01-01	2.2874800000000000
1982-01-01	2.7638500000000000
1983-01-01	3.8053300000000000
1984-01-01	4.0463700000000000
1985-01-01	3.3900600000000000
1986-01-01	3.8314100000000000
1987-01-01	5.1533500000000000
1988-01-01	6.2620500000000000
1989-01-01	6.0844300000000000
1990-01-01	5.6463600000000000
1991-01-01	5.1619300000000000
1992-01-01	4.9404300000000000
1993-01-01	2.7996400000000000
1994-01-01	2.5589000000000000
1995-01-01	5.3741400000000010
1996-01-01	5.4248300000000000
1997-01-01	4.4640600000000000
1998-01-01	4.2279900000000000
1999-01-01	3.6441300000000000
2000-01-01	3.6618100000000000
2001-01-01	3.9789000000000000
2002-01-01	4.2530700000000000
2003-01-01	3.8755800000000002
2004-01-01	2.6917200000000000
2005-01-01	1.9428299999999998
2006-01-01	1.6046500000000000
2007-01-01	1.7442099999999998
2008-01-01	1.6447300000000000
2009-01-01	1.5691100000000000
2010-01-01	1.7373299999999998
2011-01-01	1.9327700000000000
2012-01-01	1.8929799999999999
2013-01-01	1.7517800000000000
2014-01-01	1.8065400000000000
2015-01-01	1.8757099999999998
2016-01-01	1.7970400000000002