Year	Percent
1983-01-01	13.250
1984-01-01	14.875
1985-01-01	16.050
1986-01-01	16.025
1987-01-01	15.925
1988-01-01	15.650
1989-01-01	14.300
1990-01-01	12.850
1991-01-01	14.175
1992-01-01	15.050
1993-01-01	15.400
1994-01-01	14.175
1995-01-01	12.175
1996-01-01	11.525
1997-01-01	9.875
1998-01-01	7.725
1999-01-01	5.825
2000-01-01	4.400
2001-01-01	4.050
2002-01-01	4.725
2003-01-01	5.025
2004-01-01	4.900
2005-01-01	4.600
2006-01-01	4.600
2007-01-01	5.025
2008-01-01	7.650
2009-01-01	15.150
2010-01-01	17.150
2011-01-01	17.775
2012-01-01	17.725
2013-01-01	14.925
2014-01-01	12.775
2015-01-01	10.800
2016-01-01	9.075
2017-01-01	7.100