Year	% of total
1960	46.295336787564764
1961	46.78508881661246
1962	46.69854280510018
1963	48.38581897405426
1964	47.64014640724331
1965	48.99944923811272
1966	51.65073065127187
1967	51.6913139554649
1968	53.216721019863634
1969	48.57099189974018
1970	51.032092813017925
1971	49.57889718735103
1972	69.17450365726228
1973	64.4122383252818
1974	60.50354051927616
1975	68.75
1976	65.174456879526
1977	61.51419558359621
1978	62.3400365630713
1979	63.320463320463325
1980	62.93807009121459
1981	61.16504854368932
1982	54.71215351812367
1983	51.64737310774711
1984	48.231511254019296
1985	47.29487638839125
1986	46.193218170185546
1987	44.94590417310664
1988	44.34217650243639
1989	42.89997274461707
1990	46.37863715277778
1991	48.65631578947369
1992	45.51175126903553
1993	43.613086714399365
1994	43.549010339734124
1995	40.65827794561933
1996	42.62178953626635
1997	44.363547706905635
1998	42.899137662337665
1999	44.05505718547986
2000	35.535177829099304
2001	38.30578355314197
2002	36.0550455705432
2003	34.492598672720916
2004	34.8202849656076
2005	32.4323784775298
2006	30.44937883008356
2007	26.795451434588053
2008	23.846964886964887
2009	22.34616536312849
2010	21.452457493080267
2011	24.6420782800441
2012	25.67974995688912
2013	23.06251238032354
2014	24.760871473354232
2015	20.50635095550286
2016	20.950733658801195