Year	Percent
1999-01-01	76.850
2000-01-01	78.050
2001-01-01	76.575
2002-01-01	78.525
2003-01-01	79.950
2004-01-01	80.900
2005-01-01	81.200
2006-01-01	82.300
2007-01-01	83.125
2008-01-01	84.025
2009-01-01	84.825
2010-01-01	85.700
2011-01-01	86.200
2012-01-01	86.900
2013-01-01	87.150
2014-01-01	87.325
2015-01-01	87.350
2016-01-01	87.400
2017-01-01	87.025