Year	Percent
1999-01-01	56.925
2000-01-01	57.125
2001-01-01	56.350
2002-01-01	56.900
2003-01-01	57.100
2004-01-01	58.000
2005-01-01	58.875
2006-01-01	58.875
2007-01-01	59.600
2008-01-01	59.725
2009-01-01	59.600
2010-01-01	60.300
2011-01-01	59.375
2012-01-01	59.475
2013-01-01	59.825
2014-01-01	59.875
2015-01-01	59.650
2016-01-01	59.400
2017-01-01	59.600