Year	Percent
1999-01-01	58.375
2000-01-01	58.100
2001-01-01	58.675
2002-01-01	58.425
2003-01-01	57.500
2004-01-01	57.525
2005-01-01	56.900
2006-01-01	56.600
2007-01-01	57.025
2008-01-01	57.250
2009-01-01	57.150
2010-01-01	56.225
2011-01-01	56.025
2012-01-01	55.025
2013-01-01	54.875
2014-01-01	53.550
2015-01-01	52.625
2016-01-01	51.950
2017-01-01	51.625