Year	Percent
1998-01-01	27.700
1999-01-01	27.625
2000-01-01	27.675
2001-01-01	27.950
2002-01-01	28.900
2003-01-01	30.225
2004-01-01	30.550
2005-01-01	31.400
2006-01-01	32.425
2007-01-01	33.675
2008-01-01	34.300
2009-01-01	35.600
2010-01-01	36.500
2011-01-01	37.850
2012-01-01	40.300
2013-01-01	42.675
2014-01-01	46.225
2015-01-01	48.250
2016-01-01	50.325
2017-01-01	52.225