Year	Percent
1999-01-01	81.725
2000-01-01	82.550
2001-01-01	83.625
2002-01-01	83.400
2003-01-01	82.525
2004-01-01	83.825
2005-01-01	83.775
2006-01-01	84.200
2007-01-01	85.350
2008-01-01	86.775
2009-01-01	84.875
2010-01-01	83.675
2011-01-01	83.125
2012-01-01	83.275
2013-01-01	81.900
2014-01-01	81.925
2015-01-01	82.950
2016-01-01	83.475
2017-01-01	86.100