Year	Percent
1999-01-01	52.175
2000-01-01	54.950
2001-01-01	57.725
2002-01-01	58.450
2003-01-01	59.050
2004-01-01	58.475
2005-01-01	59.350
2006-01-01	60.150
2007-01-01	59.650
2008-01-01	60.525
2009-01-01	56.400
2010-01-01	54.475
2011-01-01	53.750
2012-01-01	52.100
2013-01-01	50.500
2014-01-01	51.150
2015-01-01	54.000
2016-01-01	55.700
2017-01-01	57.800