Year	Percent
1998-01-01	58.225
1999-01-01	59.500
2000-01-01	60.525
2001-01-01	61.300
2002-01-01	61.375
2003-01-01	61.350
2004-01-01	61.475
2005-01-01	61.550
2006-01-01	61.825
2007-01-01	61.825
2008-01-01	62.475
2009-01-01	61.500
2010-01-01	60.975
2011-01-01	60.100
2012-01-01	58.475
2013-01-01	57.925
2014-01-01	59.650
2015-01-01	61.125
2016-01-01	62.450
2017-01-01	64.750