Year	Percent
2000-01-01	54.475
2001-01-01	54.375
2002-01-01	54.700
2003-01-01	54.750
2004-01-01	55.025
2005-01-01	55.400
2006-01-01	55.900
2007-01-01	55.675
2008-01-01	55.975
2009-01-01	56.175
2010-01-01	56.075
2011-01-01	56.200
2012-01-01	56.400
2013-01-01	56.775
2014-01-01	57.050
2015-01-01	57.175
2016-01-01	57.475
2017-01-01	57.750