Year	% of total
1960	94.13454680133341
1961	94.09571954319732
1962	94.21763356720112
1963	94.42413857295968
1964	94.53739930247941
1965	94.52379554232209
1966	94.43048498457715
1967	94.56634525412177
1968	94.56557653806483
1969	94.6380178626035
1970	94.54807463236828
1971	84.45071747939836
1972	84.33545928495718
1973	84.77311851172902
1974	84.1496830170751
1975	83.40228818641089
1976	83.80503982254298
1977	83.45717019694254
1978	83.27090605395131
1979	83.34838381867806
1980	82.69029401525748
1981	81.67315369405239
1982	80.98839022910686
1983	80.31095870498316
1984	79.76756585558564
1985	79.05676152464946
1986	78.75818184161187
1987	78.71931253380326
1988	78.74699658260548
1989	78.72607376098044
1990	80.76166867089796
1991	80.30420835396099
1992	80.08244068463495
1993	79.98313226153245
1994	79.7929832022258
1995	79.81737201141544
1996	79.83418787798777
1997	79.97706842880524
1998	79.75976102679348
1999	79.72722449825017
2000	79.78384868253987
2001	80.03830701139174
2002	80.05704119833653
2003	80.55352270507805
2004	80.65153868945382
2005	80.72447731597298
2006	80.8357144829528
2007	81.19416166100714
2008	81.05485545582646
2009	80.61346858226932
2010	80.7781258315195
2011	81.23056229508738
2012	81.16535015062586
2013	80.9427289687651
2014	80.91140771928029
2015	79.67629801617531