Year	Percent
1999-01-01	52.775
2000-01-01	51.575
2001-01-01	51.700
2002-01-01	51.700
2003-01-01	52.550
2004-01-01	52.100
2005-01-01	52.875
2006-01-01	54.450
2007-01-01	55.600
2008-01-01	57.075
2009-01-01	55.150
2010-01-01	53.800
2011-01-01	54.175
2012-01-01	54.375
2013-01-01	54.325
2014-01-01	55.125
2015-01-01	56.550
2016-01-01	58.200
2017-01-01	59.175