Year	Percent
1998-01-01	43.450
1999-01-01	43.225
2000-01-01	42.775
2001-01-01	42.325
2002-01-01	42.925
2003-01-01	44.400
2004-01-01	43.925
2005-01-01	44.275
2006-01-01	44.950
2007-01-01	46.225
2008-01-01	46.850
2009-01-01	48.425
2010-01-01	49.525
2011-01-01	50.550
2012-01-01	53.575
2013-01-01	56.600
2014-01-01	60.225
2015-01-01	63.300
2016-01-01	65.850
2017-01-01	67.050