Year	Percent
1998-01-01	52.175
1999-01-01	51.925
2000-01-01	51.675
2001-01-01	51.425
2002-01-01	51.150
2003-01-01	50.825
2004-01-01	50.425
2005-01-01	50.900
2006-01-01	50.925
2007-01-01	51.250
2008-01-01	50.900
2009-01-01	51.525
2010-01-01	51.775
2011-01-01	51.850
2012-01-01	50.900
2013-01-01	51.200
2014-01-01	50.925
2015-01-01	51.050
2016-01-01	50.475
2017-01-01	50.175