Year	Percent
1998-01-01	48.500
1999-01-01	49.625
2000-01-01	50.950
2001-01-01	52.775
2002-01-01	54.025
2003-01-01	54.850
2004-01-01	58.025
2005-01-01	58.000
2006-01-01	59.325
2007-01-01	59.575
2008-01-01	60.250
2009-01-01	59.125
2010-01-01	58.775
2011-01-01	59.000
2012-01-01	59.200
2013-01-01	57.950
2014-01-01	57.625
2015-01-01	57.875
2016-01-01	58.450
2017-01-01	59.025