Year	Percent
1983-01-01	29.250
1984-01-01	30.075
1985-01-01	28.300
1986-01-01	26.475
1987-01-01	26.300
1988-01-01	22.900
1989-01-01	20.350
1990-01-01	19.025
1991-01-01	17.225
1992-01-01	17.375
1993-01-01	21.975
1994-01-01	24.975
1995-01-01	25.575
1996-01-01	26.375
1997-01-01	26.350
1998-01-01	24.475
1999-01-01	22.775
2000-01-01	19.300
2001-01-01	17.650
2002-01-01	18.275
2003-01-01	21.200
2004-01-01	22.400
2005-01-01	22.075
2006-01-01	22.350
2007-01-01	20.900
2008-01-01	18.500
2009-01-01	22.450
2010-01-01	22.300
2011-01-01	18.700
2012-01-01	18.750
2013-01-01	22.425
2014-01-01	22.425
2015-01-01	19.975
2016-01-01	18.125
2017-01-01	18.175