Year	Percent
1998-01-01	35.600
1999-01-01	35.800
2000-01-01	36.250
2001-01-01	36.125
2002-01-01	37.250
2003-01-01	38.350
2004-01-01	39.100
2005-01-01	39.775
2006-01-01	41.025
2007-01-01	41.475
2008-01-01	42.375
2009-01-01	42.750
2010-01-01	42.000
2011-01-01	39.325
2012-01-01	36.325
2013-01-01	34.700
2014-01-01	35.700
2015-01-01	36.975
2016-01-01	37.625
2017-01-01	38.475