Year	% of total
1965	94.76997545249218
1966	95.17447278332055
1967	95.03011031541064
1968	95.52888847134626
1969	94.72307524417592
1970	95.57362105946304
1971	95.1468251783866
1972	95.2108749776653
1973	95.06746224369135
1974	95.32232029461004
1975	96.35971524017552
1976	96.28900225266966
1977	96.52252220901121
1978	96.94383086456291
1979	96.15543652002265
1980	95.90673972346406
1981	95.50330427202015
1982	95.33926979776113
1983	92.83917205714684
1984	91.08635001661276
1985	89.11244953694964
1986	88.6043890168453
1987	85.92848967715506
1988	83.69957223333384
1989	83.14279124638904
1990	81.60450845437688
1991	81.67144749618409
1992	81.06042980288674
1993	81.89985323515498
1994	81.13193176362154
1995	81.60281715123843
1996	81.9531038009727
1997	81.88620888353755
1998	82.16912861676916
1999	81.74121510686115
2000	80.53891348429806
2001	80.98183667469253
2002	80.79182567751305
2003	83.1371684473415
2004	81.82083907348719
2005	80.36822765936401
2006	80.0627646359818
2007	78.97654982603109
2008	77.82372613060504
2009	74.16960869819745
2010	74.27192279630913
2011	73.29380076351683
2012	71.78642365120704
2013	69.54963748901078
2014	68.19240139595956
2015	69.54979369107801