Year	Percent
1965-01-01	0.000000000000000
1966-01-01	0.000000000000000
1967-01-01	0.342465753424658
1968-01-01	0.699300699300699
1969-01-01	0.337837837837838
1970-01-01	0.000000000000000
1971-01-01	0.306748466257669
1972-01-01	0.301204819277108
1973-01-01	0.288184438040346
1974-01-01	0.000000000000000
1975-01-01	0.260416666666667
1976-01-01	0.503778337531486
1977-01-01	0.486618004866180
1978-01-01	2.158273381294960
1979-01-01	2.298850574712640
1980-01-01	2.739726027397260
1981-01-01	4.260089686098660
1982-01-01	4.575163398692810
1983-01-01	6.382978723404260
1984-01-01	6.444906444906440
1985-01-01	4.761904761904760
1986-01-01	4.900000000000000
1987-01-01	4.450000000000000
1988-01-01	5.675000000000000
1989-01-01	7.100000000000000
1990-01-01	7.450000000000000
1991-01-01	9.750000000000000
1992-01-01	9.750000000000000
1993-01-01	8.975000000000000
1994-01-01	7.825000000000000
1995-01-01	6.500000000000000
1996-01-01	6.250000000000000
1997-01-01	6.850000000000000
1998-01-01	7.600000000000000
1999-01-01	6.700000000000000
2000-01-01	5.975000000000000
2001-01-01	5.425000000000000
2002-01-01	5.475000000000000
2003-01-01	5.100000000000000
2004-01-01	4.575000000000000
2005-01-01	4.150000000000000
2006-01-01	4.200000000000000
2007-01-01	3.875000000000000
2008-01-01	4.100000000000000
2009-01-01	5.800000000000000
2010-01-01	6.400000000000000
2011-01-01	6.200000000000000
2012-01-01	6.700000000000000
2013-01-01	6.400000000000000
2014-01-01	6.075000000000000
2015-01-01	5.875000000000000
2016-01-01	5.475000000000000
2017-01-01	5.200000000000000