Year	Percent
1999-01-01	52.150
2000-01-01	52.200
2001-01-01	51.350
2002-01-01	51.775
2003-01-01	51.825
2004-01-01	52.525
2005-01-01	53.300
2006-01-01	53.125
2007-01-01	53.625
2008-01-01	53.675
2009-01-01	53.475
2010-01-01	54.075
2011-01-01	53.200
2012-01-01	53.250
2013-01-01	53.525
2014-01-01	53.475
2015-01-01	53.300
2016-01-01	53.100
2017-01-01	53.825