Year	Percent
1999-01-01	47.025
2000-01-01	46.625
2001-01-01	47.225
2002-01-01	47.025
2003-01-01	46.175
2004-01-01	46.225
2005-01-01	45.600
2006-01-01	44.975
2007-01-01	45.300
2008-01-01	45.700
2009-01-01	45.725
2010-01-01	45.175
2011-01-01	44.775
2012-01-01	43.675
2013-01-01	43.025
2014-01-01	41.325
2015-01-01	40.050
2016-01-01	38.925
2017-01-01	38.175