Year	Percent
1999-01-01	60.950
2000-01-01	57.275
2001-01-01	55.800
2002-01-01	56.025
2003-01-01	55.750
2004-01-01	54.275
2005-01-01	54.750
2006-01-01	55.775
2007-01-01	57.050
2008-01-01	57.575
2009-01-01	55.825
2010-01-01	56.600
2011-01-01	58.050
2012-01-01	57.100
2013-01-01	56.400
2014-01-01	54.275
2015-01-01	53.950
2016-01-01	52.950
2017-01-01	52.175