Year	Percent
1998-01-01	67.200
1999-01-01	67.150
2000-01-01	67.825
2001-01-01	68.175
2002-01-01	67.725
2003-01-01	66.275
2004-01-01	65.400
2005-01-01	64.525
2006-01-01	64.750
2007-01-01	64.600
2008-01-01	64.450
2009-01-01	61.750
2010-01-01	60.675
2011-01-01	58.825
2012-01-01	55.975
2013-01-01	54.675
2014-01-01	55.825
2015-01-01	56.325
2016-01-01	57.050
2017-01-01	59.100