Year	Percent
1998-01-01	58.025
1999-01-01	57.950
2000-01-01	59.425
2001-01-01	62.075
2002-01-01	64.750
2003-01-01	66.025
2004-01-01	68.475
2005-01-01	71.100
2006-01-01	70.850
2007-01-01	73.125
2008-01-01	73.900
2009-01-01	73.900
2010-01-01	74.725
2011-01-01	75.900
2012-01-01	74.050
2013-01-01	73.925
2014-01-01	73.925
2015-01-01	72.650
2016-01-01	73.775
2017-01-01	73.425