Year	Percent
1960-01-01	3.71
1961-01-01	3.18
1962-01-01	4.00
1963-01-01	4.00
1964-01-01	4.25
1965-01-01	4.75
1966-01-01	5.25
1967-01-01	6.00
1968-01-01	6.50
1969-01-01	8.00
1970-01-01	6.00
1971-01-01	4.75
1972-01-01	4.75
1973-01-01	7.25
1974-01-01	8.75
1975-01-01	9.00
1976-01-01	8.50
1977-01-01	7.50
1978-01-01	10.75
1979-01-01	14.00
1980-01-01	17.26
1981-01-01	14.66
1982-01-01	10.26
1983-01-01	10.04
1984-01-01	10.16
1985-01-01	9.49
1986-01-01	8.49
1987-01-01	8.66
1988-01-01	11.17
1989-01-01	12.47
1990-01-01	11.78
1991-01-01	7.67
1992-01-01	7.36
1993-01-01	4.11
1994-01-01	7.43
1995-01-01	5.79
1996-01-01	3.25
1997-01-01	4.50
1998-01-01	5.25
1999-01-01	5.00
2000-01-01	6.00
2001-01-01	2.50
2002-01-01	3.00
2003-01-01	3.00
2004-01-01	2.75
2005-01-01	3.50
2006-01-01	4.50
2007-01-01	4.50
2008-01-01	1.75
2009-01-01	0.50
2010-01-01	1.25
2011-01-01	1.25
2012-01-01	1.25
2013-01-01	1.25
2014-01-01	1.25
2015-01-01	0.75
2016-01-01	0.75
2017-01-01	1.25