Year	Percent
1998-01-01	41.750
1999-01-01	43.225
2000-01-01	45.875
2001-01-01	50.300
2002-01-01	52.075
2003-01-01	53.750
2004-01-01	54.900
2005-01-01	56.625
2006-01-01	58.525
2007-01-01	58.775
2008-01-01	59.675
2009-01-01	59.125
2010-01-01	60.175
2011-01-01	60.875
2012-01-01	62.250
2013-01-01	62.925
2014-01-01	63.750
2015-01-01	65.225
2016-01-01	66.400
2017-01-01	67.850