Year	Percent
1998-01-01	14.950
1999-01-01	15.000
2000-01-01	15.325
2001-01-01	16.275
2002-01-01	17.300
2003-01-01	18.425
2004-01-01	19.675
2005-01-01	20.800
2006-01-01	21.825
2007-01-01	22.950
2008-01-01	23.900
2009-01-01	25.250
2010-01-01	26.075
2011-01-01	28.050
2012-01-01	30.825
2013-01-01	33.200
2014-01-01	36.575
2015-01-01	37.900
2016-01-01	39.750
2017-01-01	42.300