Year	Percent
1998-01-01	49.825
1999-01-01	50.400
2000-01-01	50.800
2001-01-01	50.300
2002-01-01	51.500
2003-01-01	51.675
2004-01-01	50.225
2005-01-01	50.400
2006-01-01	50.050
2007-01-01	51.025
2008-01-01	50.700
2009-01-01	49.675
2010-01-01	49.475
2011-01-01	47.800
2012-01-01	46.525
2013-01-01	46.925
2014-01-01	47.825
2015-01-01	49.900
2016-01-01	52.075
2017-01-01	56.225