Year	Percent
1983-01-01	23.900
1984-01-01	24.325
1985-01-01	22.050
1986-01-01	20.250
1987-01-01	19.625
1988-01-01	17.600
1989-01-01	15.550
1990-01-01	14.550
1991-01-01	14.125
1992-01-01	15.375
1993-01-01	20.650
1994-01-01	23.125
1995-01-01	22.825
1996-01-01	22.125
1997-01-01	22.025
1998-01-01	22.075
1999-01-01	20.350
2000-01-01	16.625
2001-01-01	16.700
2002-01-01	17.700
2003-01-01	21.725
2004-01-01	21.100
2005-01-01	21.475
2006-01-01	20.475
2007-01-01	18.875
2008-01-01	17.825
2009-01-01	21.900
2010-01-01	22.400
2011-01-01	18.675
2012-01-01	19.675
2013-01-01	23.675
2014-01-01	23.300
2015-01-01	22.100
2016-01-01	20.125
2017-01-01	19.300