Year	Percent
1987-01-01	7.21
1988-01-01	7.06
1989-01-01	7.74
1990-01-01	9.30
1991-01-01	9.00
1992-01-01	8.84
1993-01-01	7.58
1994-01-01	7.54
1995-01-01	7.44
1996-01-01	6.49
1997-01-01	5.77
1998-01-01	5.07
1999-01-01	4.83
2000-01-01	5.91
2001-01-01	5.37
2002-01-01	5.29
2003-01-01	4.34
2004-01-01	4.24
2005-01-01	3.55
2006-01-01	4.10
2007-01-01	4.76
2008-01-01	5.45
2009-01-01	4.52
2010-01-01	3.44
2011-01-01	3.93
2012-01-01	2.60
2013-01-01	2.08