Year	Percent
1999-01-01	27.650
2000-01-01	28.850
2001-01-01	28.675
2002-01-01	29.075
2003-01-01	30.275
2004-01-01	27.150
2005-01-01	29.950
2006-01-01	32.975
2007-01-01	35.950
2008-01-01	38.800
2009-01-01	39.425
2010-01-01	41.175
2011-01-01	39.925
2012-01-01	41.600
2013-01-01	43.750
2014-01-01	45.100
2015-01-01	46.275
2016-01-01	49.175
2017-01-01	51.275