Year	Percent
1998-01-01	43.025
1999-01-01	43.825
2000-01-01	43.825
2001-01-01	43.150
2002-01-01	44.250
2003-01-01	45.200
2004-01-01	46.750
2005-01-01	47.050
2006-01-01	47.575
2007-01-01	47.625
2008-01-01	47.900
2009-01-01	49.350
2010-01-01	50.225
2011-01-01	50.100
2012-01-01	50.575
2013-01-01	50.550
2014-01-01	51.100
2015-01-01	51.975
2016-01-01	52.325
2017-01-01	52.050