Year	Percent
1984-01-01	9.5
1985-01-01	9.5
1986-01-01	9.4
1987-01-01	9.1
1988-01-01	7.5
1989-01-01	6.5
1990-01-01	6.2
1991-01-01	7.5
1992-01-01	8.6
1993-01-01	8.8
1994-01-01	8.1
1995-01-01	7.3
1996-01-01	6.7
1997-01-01	5.6
1998-01-01	4.9
1999-01-01	4.7
2000-01-01	4.2
2001-01-01	3.8
2002-01-01	3.9
2003-01-01	3.7
2004-01-01	3.4
2005-01-01	3.3
2006-01-01	3.8
2007-01-01	3.7
2008-01-01	4.0
2009-01-01	5.6
2010-01-01	5.8
2011-01-01	5.8
2012-01-01	5.7