Year	Percent
1998-01-01	41.025
1999-01-01	42.450
2000-01-01	43.425
2001-01-01	43.225
2002-01-01	42.950
2003-01-01	43.550
2004-01-01	43.800
2005-01-01	43.250
2006-01-01	42.925
2007-01-01	42.625
2008-01-01	42.600
2009-01-01	43.025
2010-01-01	43.975
2011-01-01	44.200
2012-01-01	44.000
2013-01-01	44.450
2014-01-01	44.525
2015-01-01	44.400
2016-01-01	45.000
2017-01-01	44.800