Year	Percent
1971-01-01	0.08429600000000001
1972-01-01	0.08231700000000000
1973-01-01	0.07907300000000000
1974-01-01	0.08056600000000000
1975-01-01	0.08587400000000000
1976-01-01	0.08690600000000000
1977-01-01	0.08954300000000000
1978-01-01	0.09914099999999999
1979-01-01	0.09672300000000000
1980-01-01	0.25142000000000000
1981-01-01	0.26555100000000004
1982-01-01	0.28847700000000000
1983-01-01	0.27593500000000000
1984-01-01	0.27250400000000000
1985-01-01	0.27720300000000003
1986-01-01	0.26662800000000003
1987-01-01	0.27698100000000000
1988-01-01	0.27465800000000000
1989-01-01	0.26920500000000000
1990-01-01	0.27626900000000000
1991-01-01	0.25904000000000000
1992-01-01	0.23174299999999998
1993-01-01	0.21240400000000000
1994-01-01	0.19986300000000000
1995-01-01	0.17390600000000000
1996-01-01	0.17290700000000000
1997-01-01	0.17268499999999998
1998-01-01	0.17421500000000000
1999-01-01	0.17073900000000000
2000-01-01	0.18483600000000000
2001-01-01	0.19896200000000000
2002-01-01	0.22359400000000001
2003-01-01	0.22925300000000000
2004-01-01	0.23094800000000001
2005-01-01	0.23994400000000002
2006-01-01	0.24920599999999998
2007-01-01	0.28401300000000000
2008-01-01	0.29245500000000000
2009-01-01	0.36083200000000004
2010-01-01	0.37434200000000000
2011-01-01	0.40789899999999996
2012-01-01	0.41318400000000000
2013-01-01	0.43697900000000000
2014-01-01	0.43871300000000000
2015-01-01	0.46840500000000000
2016-01-01	0.47291900000000000
2017-01-01	0.45621200000000000