Year	% of total
1960	4.833836858006042
1961	4.026845637583892
1962	3.669724770642202
1963	2.247191011235955
1964	2.5210084033613445
1965	1.3123359580052496
1966	0.9803921568627451
1967	0.7614213197969543
1968	0.6896551724137931
1969	0.2898550724637681
1970	0.2638522427440633
1971	0.24875621890547264
1972	0.24691358024691357
1973	0.20920502092050208
1974	0
1975	0
1976	0
1977	0
1978	0
1979	2.5830258302583027
1980	3.536345776031434
1981	6.2761506276150625
1982	7.110091743119266
1983	10.663507109004739
1984	12.727272727272727
1985	15.090090090090092
1986	15.400410677618067
1987	11.881188118811883
1988	12.301587301587304
1989	12.33140655105973
1990	12.411384615384614
1991	12.863298429319373
1992	9.026461538461538
1993	8.704494949494949
1994	12.281818181818181
1995	10.45095
1996	10.661762114537444
1997	9.892372093023257
1998	11.597953488372092
1999	10.205330188679246
2000	16.608385650224218
2001	16.297777777777778
2002	16.370535714285715
2003	15.457309417040358
2004	16.754396551724138
2005	16.49349344978166
2006	14.479141630901287
2007	16.94831932773109
2008	16.316467889908257
2009	15.293649289099529
2010	17.39954081632653
2011	18.237989417989418
2012	18.926451612903225
2013	18.244679802955666
2014	16.0990243902439
2015	17.08893203883495
2016	18.06927536231884