Year	Percent
1998-01-01	53.150
1999-01-01	53.600
2000-01-01	51.750
2001-01-01	52.575
2002-01-01	57.125
2003-01-01	57.525
2004-01-01	57.175
2005-01-01	59.350
2006-01-01	59.500
2007-01-01	59.625
2008-01-01	61.925
2009-01-01	59.650
2010-01-01	58.425
2011-01-01	58.925
2012-01-01	60.350
2013-01-01	62.500
2014-01-01	64.800
2015-01-01	65.525
2016-01-01	68.200
2017-01-01	71.650