Year	Percent
1983-01-01	3.500
1984-01-01	3.800
1985-01-01	3.900
1986-01-01	4.625
1987-01-01	5.275
1988-01-01	5.600
1989-01-01	5.850
1990-01-01	5.425
1991-01-01	5.200
1992-01-01	5.500
1993-01-01	6.575
1994-01-01	7.525
1995-01-01	8.100
1996-01-01	8.250
1997-01-01	8.500
1998-01-01	8.700
1999-01-01	8.525
2000-01-01	7.925
2001-01-01	7.275
2002-01-01	6.925
2003-01-01	6.825
2004-01-01	6.475
2005-01-01	6.250
2006-01-01	5.500
2007-01-01	4.925
2008-01-01	5.550
2009-01-01	6.400
2010-01-01	6.925
2011-01-01	6.875
2012-01-01	8.850
2013-01-01	10.225
2014-01-01	10.625
2015-01-01	10.025
2016-01-01	10.000
2017-01-01	9.750