Year	Percent
1998-01-01	63.200
1999-01-01	61.625
2000-01-01	62.275
2001-01-01	61.675
2002-01-01	61.975
2003-01-01	62.150
2004-01-01	59.100
2005-01-01	58.125
2006-01-01	58.175
2007-01-01	58.650
2008-01-01	58.350
2009-01-01	57.450
2010-01-01	55.825
2011-01-01	54.200
2012-01-01	51.675
2013-01-01	53.525
2014-01-01	54.275
2015-01-01	55.950
2016-01-01	58.475
2017-01-01	63.025