Year	Percent
1998-01-01	57.450
1999-01-01	57.900
2000-01-01	58.625
2001-01-01	59.100
2002-01-01	58.900
2003-01-01	58.075
2004-01-01	57.550
2005-01-01	57.175
2006-01-01	57.325
2007-01-01	57.275
2008-01-01	57.350
2009-01-01	55.575
2010-01-01	54.650
2011-01-01	52.825
2012-01-01	50.800
2013-01-01	49.700
2014-01-01	50.650
2015-01-01	51.325
2016-01-01	51.950
2017-01-01	53.750