Year	Percent
1999-01-01	56.350
2000-01-01	56.950
2001-01-01	57.450
2002-01-01	57.100
2003-01-01	56.200
2004-01-01	57.025
2005-01-01	57.200
2006-01-01	58.175
2007-01-01	58.125
2008-01-01	58.650
2009-01-01	57.425
2010-01-01	55.925
2011-01-01	55.175
2012-01-01	54.600
2013-01-01	54.300
2014-01-01	54.075
2015-01-01	54.100
2016-01-01	55.475
2017-01-01	54.775