Year	Percent
1998-01-01	49.050
1999-01-01	50.325
2000-01-01	50.500
2001-01-01	49.800
2002-01-01	51.200
2003-01-01	52.275
2004-01-01	54.150
2005-01-01	54.450
2006-01-01	54.950
2007-01-01	54.850
2008-01-01	55.025
2009-01-01	56.475
2010-01-01	57.500
2011-01-01	57.450
2012-01-01	58.275
2013-01-01	58.300
2014-01-01	59.000
2015-01-01	59.925
2016-01-01	60.450
2017-01-01	60.250