Year	Percent
1998-01-01	46.275
1999-01-01	46.025
2000-01-01	46.250
2001-01-01	45.875
2002-01-01	46.425
2003-01-01	47.150
2004-01-01	47.250
2005-01-01	47.625
2006-01-01	48.300
2007-01-01	48.475
2008-01-01	48.875
2009-01-01	48.300
2010-01-01	46.700
2011-01-01	43.250
2012-01-01	39.550
2013-01-01	37.750
2014-01-01	38.100
2015-01-01	39.025
2016-01-01	39.900
2017-01-01	40.900