Year	Percent
1998-01-01	58.975
1999-01-01	57.550
2000-01-01	56.575
2001-01-01	56.775
2002-01-01	57.050
2003-01-01	56.450
2004-01-01	56.200
2005-01-01	56.750
2006-01-01	57.075
2007-01-01	57.375
2008-01-01	57.400
2009-01-01	56.975
2010-01-01	56.025
2011-01-01	55.800
2012-01-01	56.000
2013-01-01	55.550
2014-01-01	55.475
2015-01-01	55.600
2016-01-01	55.000
2017-01-01	55.200