Year	Percent
1998-01-01	44.575
1999-01-01	45.500
2000-01-01	46.300
2001-01-01	47.275
2002-01-01	47.900
2003-01-01	48.350
2004-01-01	50.800
2005-01-01	50.475
2006-01-01	50.800
2007-01-01	50.650
2008-01-01	51.650
2009-01-01	51.125
2010-01-01	51.075
2011-01-01	51.450
2012-01-01	53.425
2013-01-01	53.575
2014-01-01	54.400
2015-01-01	54.100
2016-01-01	55.200
2017-01-01	55.950