Year	Percent
1998-01-01	56.975
1999-01-01	56.175
2000-01-01	56.175
2001-01-01	56.850
2002-01-01	55.750
2003-01-01	54.800
2004-01-01	53.250
2005-01-01	52.950
2006-01-01	52.425
2007-01-01	52.375
2008-01-01	52.100
2009-01-01	50.650
2010-01-01	49.775
2011-01-01	49.900
2012-01-01	49.425
2013-01-01	49.450
2014-01-01	48.900
2015-01-01	48.025
2016-01-01	47.675
2017-01-01	47.950