Year	Percent
1999-01-01	51.950
2000-01-01	52.575
2001-01-01	53.000
2002-01-01	52.575
2003-01-01	52.900
2004-01-01	52.550
2005-01-01	51.325
2006-01-01	50.725
2007-01-01	50.625
2008-01-01	50.975
2009-01-01	50.300
2010-01-01	50.800
2011-01-01	50.150
2012-01-01	50.700
2013-01-01	51.050
2014-01-01	51.075
2015-01-01	51.950
2016-01-01	52.550
2017-01-01	52.650