Year	Percent
1998-01-01	23.950
1999-01-01	24.425
2000-01-01	23.650
2001-01-01	24.575
2002-01-01	27.200
2003-01-01	29.950
2004-01-01	31.325
2005-01-01	32.975
2006-01-01	34.000
2007-01-01	35.200
2008-01-01	36.100
2009-01-01	37.175
2010-01-01	37.950
2011-01-01	39.400
2012-01-01	41.550
2013-01-01	44.225
2014-01-01	46.350
2015-01-01	48.250
2016-01-01	51.225
2017-01-01	54.550