Year	Percent
1998-01-01	38.900
1999-01-01	39.800
2000-01-01	42.925
2001-01-01	46.550
2002-01-01	48.475
2003-01-01	51.025
2004-01-01	51.425
2005-01-01	52.800
2006-01-01	54.800
2007-01-01	55.100
2008-01-01	57.075
2009-01-01	54.625
2010-01-01	55.600
2011-01-01	56.750
2012-01-01	56.625
2013-01-01	56.475
2014-01-01	56.775
2015-01-01	57.400
2016-01-01	59.800
2017-01-01	61.625