Year	Percent
1998-01-01	40.475
1999-01-01	40.975
2000-01-01	41.650
2001-01-01	41.575
2002-01-01	43.000
2003-01-01	44.275
2004-01-01	45.250
2005-01-01	45.975
2006-01-01	47.300
2007-01-01	47.675
2008-01-01	48.575
2009-01-01	48.900
2010-01-01	48.025
2011-01-01	44.975
2012-01-01	41.725
2013-01-01	39.900
2014-01-01	41.100
2015-01-01	42.475
2016-01-01	43.325
2017-01-01	44.425