Year	Percent
1998-01-01	52.150
1999-01-01	52.350
2000-01-01	52.175
2001-01-01	51.425
2002-01-01	51.775
2003-01-01	52.250
2004-01-01	52.850
2005-01-01	52.875
2006-01-01	53.100
2007-01-01	52.925
2008-01-01	52.975
2009-01-01	53.425
2010-01-01	53.500
2011-01-01	52.675
2012-01-01	52.325
2013-01-01	52.050
2014-01-01	51.825
2015-01-01	52.000
2016-01-01	52.125
2017-01-01	52.100