Year	Percent
1978-12-31	11.125
1979-12-31	17.19
1980-12-31	14.435
1981-12-31	14.815
1982-12-31	10.315
1983-12-31	9.315
1984-12-31	9.69
1985-12-31	11.69
1986-12-31	11.19
1987-12-31	8.595
1988-12-31	12.94
1989-12-31	14.755
1990-12-31	14.315
1991-12-31	10.44
1992-12-31	6.125
1993-12-31	5.28
1994-12-31	5.315
1995-12-31	6.41
1996-12-31	6.06
1997-12-31	7.345
1998-12-31	6.345
1999-12-31	3.6875
2000-12-31	5.2188
2001-12-31	4.4688
2002-12-31	4.2813
2003-12-31	3.6875
2004-12-31	4.755
2005-12-31	4.715
2006-12-31	5.23
2007-12-31	5.8
2008-12-31	1.75
2009-12-31	0.5
2010-12-31	0.575
2011-12-31	0.65
2012-12-31	0.45
2013-12-31	0.475
2014-12-31	0.45
2015-12-31	0.425
2016-12-31	0.24