Year	Percent
1998-01-01	45.8
1999-01-01	44.7
2000-01-01	34.6
2001-01-01	33.6
2002-01-01	50.6
2003-01-01	51.9
2004-01-01	63.8
2005-01-01	78.4
2006-01-01	79.6
2007-01-01	67.8
2008-01-01	63.4
2009-01-01	52
2010-01-01	52.4
2011-01-01	52.3
2012-01-01	69.4
2013-01-01	77.0
2014-01-01	77.6
2015-01-01	74.7