Year	Percent
1998-01-01	61.425
1999-01-01	60.600
2000-01-01	61.750
2001-01-01	61.025
2002-01-01	57.575
2003-01-01	55.775
2004-01-01	54.925
2005-01-01	53.125
2006-01-01	52.250
2007-01-01	51.750
2008-01-01	50.475
2009-01-01	50.325
2010-01-01	50.275
2011-01-01	49.400
2012-01-01	47.625
2013-01-01	45.200
2014-01-01	43.175
2015-01-01	42.025
2016-01-01	39.150
2017-01-01	36.350