Year	Percent
1960-01-01	4.50
1961-01-01	4.50
1962-01-01	4.50
1963-01-01	4.50
1964-01-01	4.50
1965-01-01	4.92
1966-01-01	6.00
1967-01-01	6.00
1968-01-01	6.60
1969-01-01	8.50
1970-01-01	6.92
1971-01-01	5.49
1972-01-01	5.79
1973-01-01	9.75
1974-01-01	10.50
1975-01-01	7.26
1976-01-01	6.35
1977-01-01	7.75
1978-01-01	11.55
1979-01-01	15.30
1980-01-01	20.35
1981-01-01	15.75
1982-01-01	11.50
1983-01-01	11.00
1984-01-01	11.06
1985-01-01	9.50
1986-01-01	7.50
1987-01-01	8.75
1988-01-01	10.50
1989-01-01	10.50
1990-01-01	10.00
1991-01-01	7.21
1992-01-01	6.00
1993-01-01	6.00
1994-01-01	8.50
1995-01-01	8.65
1996-01-01	8.25
1997-01-01	8.50
1998-01-01	7.75
1999-01-01	8.50
2000-01-01	9.50
2001-01-01	4.84
2002-01-01	4.25
2003-01-01	4.00
2004-01-01	5.15
2005-01-01	7.15
2006-01-01	8.25
2007-01-01	7.33
2008-01-01	3.61
2009-01-01	3.25
2010-01-01	3.25
2011-01-01	3.25
2012-01-01	3.25
2013-01-01	3.25
2014-01-01	3.25
2015-01-01	3.37
2016-01-01	3.64
2017-01-01	4.40