Year	Percent
1990-01-01	0.8
1991-01-01	4.4
1992-01-01	2.8
1993-01-01	4.4
1994-01-01	4.3
1995-01-01	4.1
1996-01-01	3.9
1997-01-01	4.8
1998-01-01	6.4
1999-01-01	8.6
2000-01-01	8.7
2001-01-01	8.0
2002-01-01	7.3
2003-01-01	7.8
2004-01-01	8.3
2005-01-01	7.9
2006-01-01	7.2
2007-01-01	5.3
2008-01-01	4.4
2009-01-01	6.7
2010-01-01	7.3
2011-01-01	6.8