Year	% of total
1960	99.92451651526588
1961	99.9123934767296
1962	99.48767596357871
1963	98.78300810443488
1964	98.19268618982609
1965	97.93904088788273
1966	97.3875971517582
1967	97.2177129063678
1968	97.20080656633077
1969	96.98460145151671
1970	96.56297917027922
1971	96.09184349944894
1972	95.98769206227867
1973	95.9587275260519
1974	94.8594893052361
1975	94.33700818640685
1976	93.9999994803147
1977	93.51444535475505
1978	93.8330240928732
1979	93.18829057425853
1980	92.30693376119102
1981	90.9439285890912
1982	89.8234867320515
1983	88.71379639483789
1984	88.95788561519294
1985	89.1024049387298
1986	89.176524500147
1987	88.44921707334301
1988	88.12741505996358
1989	88.89654974813655
1990	89.17085254370785
1991	89.306984358692
1992	89.32659978080349
1993	89.34209304611147
1994	87.94841452118628
1995	84.91984747613401
1996	85.62631274609342
1997	84.28297118912043
1998	82.71809005812803
1999	83.01312235275314
2000	83.44341261908087
2001	84.98340817811128
2002	89.84916727310078
2003	89.7010316967833
2004	91.25833829805937
2005	91.16899272598678
2006	90.33412984189263
2007	88.08548397935229
2008	87.11638335810935
2009	88.70503580764448
2010	87.95743151108283
2011	87.00863718575589
2012	87.21562043147598
2013	84.5060018141859
2014	83.33175267044699
2015	80.56229520766499