Year	% of total
1960	80.6161238329836
1961	80.48705042040437
1962	79.6186483999591
1963	79.27128203907756
1964	77.77615500705906
1965	77.61428161110007
1966	75.33784505027647
1967	76.48711943793911
1968	73.11644841153327
1969	71.55024898579147
1970	70.03532772098617
1971	68.22286742309542
1972	68.23155130622138
1973	67.94978669151178
1974	69.44281988461233
1975	70.76305688030709
1976	70.83617154375477
1977	70.36584404320745
1978	68.25818318415565
1979	67.29740745772762
1980	69.51525696869197
1981	68.6565225860912
1982	67.42739677179145
1983	67.92396188410288
1984	65.97821260192175
1985	65.66713935799923
1986	66.03890015306817
1987	66.0918849936191
1988	66.50332249006034
1989	64.88470331925242
1990	72.07915908121177
1991	71.58662166167221
1992	72.2077717132612
1993	73.42992290833294
1994	73.27656908205539
1995	70.41025947915261
1996	71.84906555772994
1997	71.06118189122073
1998	69.03476917947681
1999	68.58189217887599
2000	67.40287437378348
2001	67.5012785675347
2002	67.05151813109474
2003	68.15149947336818
2004	68.16695950109916
2005	70.14530666057271
2006	70.47132938027589
2007	69.7498475413517
2008	70.75717398938113
2009	69.3911244923591
2010	65.66539581219112
2011	68.76645462289869
2012	71.44345143222412
2013	67.42655442061003
2014	69.62558522511898
2015	69.20933397512813
2016	69.46453015646183