Year	Percent
1981-12-31	13.625
1982-12-31	9.25
1983-12-31	9.9375
1984-12-31	8.6875
1985-12-31	7.9375
1986-12-31	6.3125
1987-12-31	7.3755
1988-12-31	9.2505
1989-12-31	8.3438
1990-12-31	7.5313
1991-12-31	4.2188
1992-12-31	3.3738
1993-12-31	3.3125
1994-12-31	6.44
1995-12-31	5.535
1996-12-31	5.495
1997-12-31	5.685
1998-12-31	5
1999-12-31	5.98
2000-12-31	6.35
2001-12-31	1.83
2002-12-31	1.345
2003-12-31	1.1
2004-12-31	2.56
2005-12-31	4.505
2006-12-31	5.34
2007-12-31	4.77
2008-12-31	1.41
2009-12-31	0.48
2010-12-31	0.43
2011-12-31	0.68
2012-12-31	0.415
2013-12-31	0.32
2014-12-31	0.425
2015-12-31	0.76
2016-12-31	0.995
2017-12-31	1.76
2018-12-31	2.87
2019-12-31	1.92