Year	Percent
1998-01-01	39.025
1999-01-01	37.375
2000-01-01	35.425
2001-01-01	32.175
2002-01-01	31.400
2003-01-01	30.900
2004-01-01	27.250
2005-01-01	27.575
2006-01-01	25.350
2007-01-01	23.300
2008-01-01	24.675
2009-01-01	28.475
2010-01-01	29.325
2011-01-01	32.025
2012-01-01	37.525
2013-01-01	41.350
2014-01-01	44.650
2015-01-01	42.575
2016-01-01	39.625
2017-01-01	37.325