Year	Percent
1999-01-01	58.775
2000-01-01	58.450
2001-01-01	58.575
2002-01-01	58.950
2003-01-01	59.475
2004-01-01	57.925
2005-01-01	58.575
2006-01-01	59.075
2007-01-01	59.925
2008-01-01	60.175
2009-01-01	60.425
2010-01-01	60.400
2011-01-01	60.475
2012-01-01	60.750
2013-01-01	60.925
2014-01-01	60.675
2015-01-01	60.750
2016-01-01	61.225
2017-01-01	61.200