Year	% of total
1960	0.7299270072992701
1961	0.352112676056338
1962	0.33333333333333337
1963	0.3021148036253776
1964	0.2475247524752475
1965	0.24271844660194172
1966	0.21691973969631234
1967	0
1968	0.16835016835016833
1969	0.14388489208633093
1970	0.14749262536873153
1971	0.11976047904191614
1972	0
1973	0
1974	0
1975	0.09033423667570009
1976	0
1977	0
1978	0
1979	0.07739938080495355
1980	0.07855459544383346
1981	0.07651109410864575
1982	0.08431703204047217
1983	0.08547008547008546
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0
1998	0
1999	0
2000	0
2001	0
2002	0
2003	0
2004	0
2005	0
2006	0
2007	0
2008	0
2009	0
2010	0
2011	0
2012	0
2013	0
2014	0
2015	0
2016	0