Year	Percent
1999-01-01	59.675
2000-01-01	60.075
2001-01-01	61.200
2002-01-01	60.350
2003-01-01	59.425
2004-01-01	62.000
2005-01-01	61.975
2006-01-01	62.450
2007-01-01	63.750
2008-01-01	63.025
2009-01-01	61.600
2010-01-01	60.425
2011-01-01	58.500
2012-01-01	57.725
2013-01-01	57.125
2014-01-01	57.650
2015-01-01	57.850
2016-01-01	56.725
2017-01-01	59.500