Year	Percent
1999-01-01	53.875
2000-01-01	54.575
2001-01-01	54.150
2002-01-01	54.125
2003-01-01	54.525
2004-01-01	54.400
2005-01-01	54.250
2006-01-01	54.775
2007-01-01	54.525
2008-01-01	53.675
2009-01-01	51.925
2010-01-01	51.125
2011-01-01	51.875
2012-01-01	52.525
2013-01-01	54.025
2014-01-01	57.175
2015-01-01	58.925
2016-01-01	61.050
2017-01-01	62.700