Year	Percent
1998-01-01	10.3
1999-01-01	12.8
2000-01-01	19.2
2001-01-01	10.3
2002-01-01	7.8
2003-01-01	6.1
2004-01-01	5.3
2005-01-01	4.1
2006-01-01	4.6
2007-01-01	3.8
2008-01-01	6.8
2009-01-01	11.5
2010-01-01	8.9
2011-01-01	7.3
2012-01-01	5.2
2013-01-01	3.6
2014-01-01	2.9
2015-01-01	2.8