Year	Percent
1998-01-01	36.275
1999-01-01	38.800
2000-01-01	41.675
2001-01-01	45.725
2002-01-01	47.850
2003-01-01	49.625
2004-01-01	50.950
2005-01-01	52.725
2006-01-01	54.550
2007-01-01	55.050
2008-01-01	56.450
2009-01-01	55.450
2010-01-01	56.250
2011-01-01	56.950
2012-01-01	58.175
2013-01-01	58.550
2014-01-01	59.125
2015-01-01	59.975
2016-01-01	61.400
2017-01-01	62.550