Year	Percent
1999-01-01	55.625
2000-01-01	56.450
2001-01-01	56.975
2002-01-01	56.500
2003-01-01	56.825
2004-01-01	56.625
2005-01-01	55.400
2006-01-01	54.875
2007-01-01	54.800
2008-01-01	55.325
2009-01-01	54.625
2010-01-01	55.200
2011-01-01	54.625
2012-01-01	55.250
2013-01-01	55.675
2014-01-01	55.800
2015-01-01	56.850
2016-01-01	57.600
2017-01-01	57.875