Year	Percent
1983-01-01	15.325
1984-01-01	16.850
1985-01-01	18.500
1986-01-01	18.625
1987-01-01	18.000
1988-01-01	17.425
1989-01-01	15.625
1990-01-01	14.575
1991-01-01	15.825
1992-01-01	16.000
1993-01-01	16.025
1994-01-01	14.650
1995-01-01	12.500
1996-01-01	11.850
1997-01-01	9.875
1998-01-01	7.325
1999-01-01	5.725
2000-01-01	4.250
2001-01-01	3.800
2002-01-01	4.125
2003-01-01	4.350
2004-01-01	4.075
2005-01-01	4.000
2006-01-01	4.200
2007-01-01	4.925
2008-01-01	5.700
2009-01-01	9.525
2010-01-01	11.425
2011-01-01	12.525
2012-01-01	12.775
2013-01-01	12.450
2014-01-01	10.900
2015-01-01	8.950
2016-01-01	7.625
2017-01-01	6.325