Year	Percent
1998-01-01	64.550
1999-01-01	63.725
2000-01-01	63.850
2001-01-01	63.475
2002-01-01	63.975
2003-01-01	64.825
2004-01-01	64.800
2005-01-01	65.275
2006-01-01	65.925
2007-01-01	66.300
2008-01-01	66.550
2009-01-01	65.375
2010-01-01	63.000
2011-01-01	58.375
2012-01-01	53.425
2013-01-01	51.350
2014-01-01	51.375
2015-01-01	52.450
2016-01-01	53.850
2017-01-01	55.425