Year	Percent
1960-01-01	6.94
1961-01-01	7.30
1962-01-01	6.57
1963-01-01	5.84
1964-01-01	6.57
1965-01-01	5.48
1966-01-01	5.48
1967-01-01	5.84
1968-01-01	5.84
1969-01-01	6.25
1970-01-01	6.00
1971-01-01	4.75
1972-01-01	4.25
1973-01-01	9.00
1974-01-01	9.00
1975-01-01	6.50
1976-01-01	6.50
1977-01-01	4.25
1978-01-01	3.50
1979-01-01	6.25
1980-01-01	7.25
1981-01-01	5.50
1982-01-01	5.50
1983-01-01	5.00
1984-01-01	5.00
1985-01-01	5.00
1986-01-01	3.00
1987-01-01	2.50
1988-01-01	2.50
1989-01-01	4.25
1990-01-01	6.00
1991-01-01	4.50
1992-01-01	3.25
1993-01-01	1.75
1994-01-01	1.75
1995-01-01	0.50
1996-01-01	0.50
1997-01-01	0.50
1998-01-01	0.50
1999-01-01	0.50
2000-01-01	0.50
2001-01-01	0.10
2002-01-01	0.10
2003-01-01	0.10
2004-01-01	0.10
2005-01-01	0.10
2006-01-01	0.40
2007-01-01	0.75
2008-01-01	0.30
2009-01-01	0.30
2010-01-01	0.30
2011-01-01	0.30
2012-01-01	0.30
2013-01-01	0.30
2014-01-01	0.30
2015-01-01	0.30
2016-01-01	0.30
2017-01-01	0.30