Year	Percent
1976-12-31	11.1569
1977-12-31	7.6303
1978-12-31	8.5348
1979-12-31	12.988
1980-12-31	15.0896
1981-12-31	13.0334
1982-12-31	11.348
1983-12-31	9.5799
1984-12-31	9.291
1985-12-31	11.5605
1986-12-31	10.3501
1987-12-31	9.2335
1988-12-31	9.8372
1989-12-31	13.2938
1990-12-31	14.093
1991-12-31	10.8211
1992-12-31	8.9078
1993-12-31	5.2074
1994-12-31	5.1617
1995-12-31	6.3291
1996-12-31	5.7791
1997-12-31	6.5
1998-12-31	6.8099
1999-12-31	5.0399
2000-12-31	5.8012
2001-12-31	4.7579
2002-12-31	3.86
2003-12-31	3.5596
2004-12-31	4.439
2005-12-31	4.5514
2006-12-31	4.6502
2007-12-31	5.5257
2008-12-31	4.2781
2009-12-31	0.4888
2010-12-31	0.4963
2011-12-31	0.4839
2012-12-31	0.3127
2013-12-31	0.2999
2014-12-31	0.3789
2015-12-31	0.4448
2016-12-31	0.322