Year	Percent
1999-01-01	61.150
2000-01-01	61.675
2001-01-01	60.925
2002-01-01	60.850
2003-01-01	61.375
2004-01-01	61.225
2005-01-01	61.750
2006-01-01	62.525
2007-01-01	62.250
2008-01-01	61.625
2009-01-01	61.400
2010-01-01	61.350
2011-01-01	61.900
2012-01-01	62.875
2013-01-01	63.875
2014-01-01	65.750
2015-01-01	67.150
2016-01-01	68.550
2017-01-01	69.575