Year	Percent
1998-01-01	68.2
1999-01-01	53.2
2000-01-01	50.1
2001-01-01	53.7
2002-01-01	64.3
2003-01-01	77.7
2004-01-01	82.5
2005-01-01	48.1
2006-01-01	47.4
2007-01-01	47.2
2008-01-01	29
2009-01-01	38.3
2010-01-01	33.9
2011-01-01	29.5
2012-01-01	26.9
2013-01-01	31.7
2014-01-01	30.4
2015-01-01	38.0