Year	Percent
1998-01-01	45.850
1999-01-01	46.450
2000-01-01	47.300
2001-01-01	48.200
2002-01-01	48.875
2003-01-01	49.375
2004-01-01	50.575
2005-01-01	50.375
2006-01-01	51.075
2007-01-01	51.225
2008-01-01	51.375
2009-01-01	50.250
2010-01-01	49.750
2011-01-01	49.800
2012-01-01	49.600
2013-01-01	48.600
2014-01-01	48.675
2015-01-01	49.225
2016-01-01	50.025
2017-01-01	50.675