Year	% of total
1960	16.1231884057971
1961	14.147909967845662
1962	14.732142857142858
1963	13.556338028169012
1964	16.545454545454547
1965	18.21247892074199
1966	18.67816091954023
1967	19.56224350205198
1968	19.212410501193318
1969	21.242937853107343
1970	23.800195886385897
1971	22.746419545071607
1972	19.16829109811566
1973	22.106722106722106
1974	27.848101265822777
1975	27.45411013567438
1976	25.703703703703706
1977	29.743589743589745
1978	32.74985883681536
1979	35.37941034316095
1980	44.9645390070922
1981	36.06393606393606
1982	39.438033115905675
1983	40.7015857760692
1984	43.48641049671978
1985	47.27780362959516
1986	46.06281292671825
1987	50.19704433497536
1988	54.85485485485485
1989	45.183673469387756
1990	41.337090909090904
1991	36.045450121654504
1992	35.68776785714285
1993	29.05256038647343
1994	7.882336448598131
1995	8.274256410256411
1996	5.770406091370559
1997	2.973243243243243
1998	3.055833333333333
1999	3.704040404040404
2000	2.19788643533123
2001	2.505403726708075
2002	2.249093333333333
2003	2.0520924574209247
2004	1.9659906759906758
2005	1.8019656019656023
2006	1.8108641975308641
2007	1.7379146919431279
2008	2.462254196642686
2009	8.997731481481482
2010	9.367663755458516
2011	10.62265873015873
2012	13.691200873362448
2013	11.48329853862213
2014	13.41756704980843
2015	4.484299802761341
2016	0.297525354969574