Year	Percent
1972-01-01	2.627520000000000
1973-01-01	4.740830000000000
1974-01-01	6.248540000000000
1975-01-01	12.227900000000000
1976-01-01	24.044900000000000
1977-01-01	22.403600000000000
1978-01-01	20.000999999999998
1979-01-01	18.367900000000000
1980-01-01	20.303100000000000
1981-01-01	23.557900000000000
1982-01-01	23.122900000000000
1983-01-01	22.551100000000000
1984-01-01	24.899400000000000
1985-01-01	20.468800000000000
1986-01-01	18.493200000000000
1987-01-01	13.884100000000000
1988-01-01	14.257600000000000
1989-01-01	14.856200000000000
1990-01-01	12.001600000000000
1991-01-01	10.310300000000000
1992-01-01	15.884200000000000
1993-01-01	18.554800000000000
1994-01-01	17.536900000000000
1995-01-01	18.491300000000000
1996-01-01	22.287300000000000
1997-01-01	22.841600000000000
1998-01-01	19.497900000000000
1999-01-01	20.419800000000000
2000-01-01	21.809000000000000
2001-01-01	22.408700000000000
2002-01-01	22.280100000000000
2003-01-01	21.588900000000000
2004-01-01	20.045300000000000
2005-01-01	19.230600000000000
2006-01-01	18.555800000000000
2007-01-01	19.440500000000000
2008-01-01	15.975600000000000
2009-01-01	14.547300000000000
2010-01-01	13.710100000000000
2011-01-01	12.773600000000000
2012-01-01	12.439100000000000
2013-01-01	15.904200000000000
2014-01-01	17.779100000000000
2015-01-01	14.255500000000000
2016-01-01	11.317200000000000
2017-01-01	11.061000000000000