Year	Percent
1987-12-31	7.28
1988-12-31	9.2
1989-12-31	8.26
1990-12-31	7.46
1991-12-31	4.16
1992-12-31	3.34
1993-12-31	3.29
1994-12-31	6.41
1995-12-31	5.54
1996-12-31	5.47
1997-12-31	5.7
1998-12-31	4.98
1999-12-31	5.92
2000-12-31	6.34
2001-12-31	1.81
2002-12-31	1.32
2003-12-31	1.1
2004-12-31	2.51
2005-12-31	4.5
2006-12-31	5.31
2007-12-31	4.71
2008-12-31	1.5
2009-12-31	0.25
2010-12-31	0.37
2011-12-31	0.58
2012-12-31	0.31