Year	Percent
1998-01-01	15.675
1999-01-01	15.825
2000-01-01	16.050
2001-01-01	16.925
2002-01-01	18.125
2003-01-01	19.275
2004-01-01	20.550
2005-01-01	21.500
2006-01-01	22.475
2007-01-01	23.450
2008-01-01	24.600
2009-01-01	25.975
2010-01-01	26.900
2011-01-01	28.825
2012-01-01	32.175
2013-01-01	34.650
2014-01-01	38.275
2015-01-01	39.600
2016-01-01	41.725
2017-01-01	44.525