Year	Percent
1998-01-01	41.500
1999-01-01	38.275
2000-01-01	36.350
2001-01-01	34.250
2002-01-01	32.225
2003-01-01	29.975
2004-01-01	27.775
2005-01-01	27.450
2006-01-01	27.675
2007-01-01	28.475
2008-01-01	28.075
2009-01-01	26.550
2010-01-01	25.225
2011-01-01	24.500
2012-01-01	25.200
2013-01-01	25.550
2014-01-01	27.100
2015-01-01	28.375
2016-01-01	28.625
2017-01-01	29.150