Year	Percent
1999-01-01	73.73
2000-01-01	74.68
2001-01-01	79.03
2002-01-01	74.11
2003-01-01	77.64
2004-01-01	77.16
2005-01-01	80.73
2006-01-01	80.75
2007-01-01	82.03
2008-01-01	72.83
2009-01-01	73.84
2010-01-01	66.21
2011-01-01	65.87
2012-01-01	66.28
2013-01-01	75.88
2014-01-01	78.42
2015-01-01	69.84