Year	Percent
1999-01-01	56.600
2000-01-01	56.400
2001-01-01	56.450
2002-01-01	56.625
2003-01-01	56.900
2004-01-01	54.750
2005-01-01	55.275
2006-01-01	55.975
2007-01-01	57.000
2008-01-01	57.675
2009-01-01	57.225
2010-01-01	57.500
2011-01-01	57.750
2012-01-01	57.775
2013-01-01	57.675
2014-01-01	57.275
2015-01-01	57.250
2016-01-01	57.525
2017-01-01	57.850