Year	Percent
1998-01-01	42.125
1999-01-01	42.075
2000-01-01	42.675
2001-01-01	42.350
2002-01-01	41.850
2003-01-01	39.400
2004-01-01	41.100
2005-01-01	39.175
2006-01-01	38.900
2007-01-01	39.125
2008-01-01	39.050
2009-01-01	39.825
2010-01-01	39.775
2011-01-01	42.725
2012-01-01	44.775
2013-01-01	45.025
2014-01-01	46.575
2015-01-01	45.150
2016-01-01	42.750
2017-01-01	40.150