Year	Percent
1998-01-01	39.025
1999-01-01	39.350
2000-01-01	38.925
2001-01-01	38.425
2002-01-01	39.600
2003-01-01	41.775
2004-01-01	39.875
2005-01-01	41.950
2006-01-01	42.575
2007-01-01	42.675
2008-01-01	42.975
2009-01-01	42.375
2010-01-01	42.350
2011-01-01	39.475
2012-01-01	36.450
2013-01-01	35.550
2014-01-01	34.050
2015-01-01	34.325
2016-01-01	36.300
2017-01-01	38.250