Year	Percent
1998-01-01	56.550
1999-01-01	56.775
2000-01-01	57.225
2001-01-01	57.675
2002-01-01	57.075
2003-01-01	55.600
2004-01-01	56.075
2005-01-01	55.725
2006-01-01	55.050
2007-01-01	53.775
2008-01-01	53.150
2009-01-01	51.575
2010-01-01	50.475
2011-01-01	49.450
2012-01-01	46.425
2013-01-01	43.400
2014-01-01	39.775
2015-01-01	36.700
2016-01-01	34.150
2017-01-01	32.950