Year	Percent
1999-01-01	82.275
2000-01-01	82.400
2001-01-01	81.200
2002-01-01	81.925
2003-01-01	82.300
2004-01-01	83.375
2005-01-01	84.550
2006-01-01	84.475
2007-01-01	85.300
2008-01-01	85.700
2009-01-01	85.575
2010-01-01	86.325
2011-01-01	84.750
2012-01-01	85.000
2013-01-01	85.350
2014-01-01	85.625
2015-01-01	85.075
2016-01-01	85.125
2017-01-01	84.875