Year	Percent
1999-01-01	57.075
2000-01-01	57.975
2001-01-01	57.325
2002-01-01	56.775
2003-01-01	55.900
2004-01-01	56.550
2005-01-01	56.700
2006-01-01	56.350
2007-01-01	57.000
2008-01-01	56.925
2009-01-01	55.725
2010-01-01	55.825
2011-01-01	55.475
2012-01-01	55.175
2013-01-01	54.550
2014-01-01	53.900
2015-01-01	53.525
2016-01-01	54.000
2017-01-01	54.975