Year	Percent
1999-01-01	49.025
2000-01-01	48.950
2001-01-01	49.600
2002-01-01	50.525
2003-01-01	51.125
2004-01-01	50.350
2005-01-01	51.300
2006-01-01	51.975
2007-01-01	52.850
2008-01-01	53.375
2009-01-01	54.075
2010-01-01	54.125
2011-01-01	54.525
2012-01-01	55.025
2013-01-01	55.300
2014-01-01	55.300
2015-01-01	55.350
2016-01-01	55.925
2017-01-01	55.900