Year	Percent
1999-01-01	54.400
2000-01-01	54.700
2001-01-01	55.475
2002-01-01	56.625
2003-01-01	57.275
2004-01-01	56.475
2005-01-01	57.500
2006-01-01	58.225
2007-01-01	59.175
2008-01-01	59.750
2009-01-01	60.475
2010-01-01	60.550
2011-01-01	60.900
2012-01-01	61.400
2013-01-01	61.675
2014-01-01	61.800
2015-01-01	62.150
2016-01-01	63.000
2017-01-01	63.150