Year	Percent
1998-01-01	38.600
1999-01-01	39.400
2000-01-01	40.075
2001-01-01	40.875
2002-01-01	41.400
2003-01-01	41.775
2004-01-01	43.800
2005-01-01	43.375
2006-01-01	43.675
2007-01-01	43.550
2008-01-01	44.500
2009-01-01	44.075
2010-01-01	44.100
2011-01-01	44.475
2012-01-01	46.075
2013-01-01	46.150
2014-01-01	46.800
2015-01-01	46.575
2016-01-01	47.500
2017-01-01	48.175