Year	% of total
1971	90.28871391076116
1972	90.5
1973	91.4027149321267
1974	91.33333333333333
1975	91.8580375782881
1976	92.39766081871345
1977	92.9453262786596
1978	93.54838709677419
1979	94.0828402366864
1980	94.0828402366864
1981	94.3899018232819
1982	93.77777777777779
1983	94.39252336448598
1984	94.79553903345726
1985	94.76961394769614
1986	94.7565543071161
1987	95.02890173410404
1988	95.17396184062851
1989	95.33116178067318
1990	95.34391534391534
1991	95.45923632610939
1992	95.72243346007605
1993	95.66055930568949
1994	95.7943925233645
1995	95.93639575971731
1996	96.09310058187863
1997	96.281951975213
1998	96.38109305760709
1999	96.42346208869814
2000	90.02493765586036
2001	91.49048625792811
2002	79.74559686888453
2003	74.95344506517691
2004	78.00353356890459
2005	81.8003144654088
2006	87.00287002870029
2007	90.06024096385542
2008	88.60531991373112
2009	88.13855843247026
2010	86.37841352405722
2011	86.03617899079657
2012	86.72463768115942
2013	87.7843302443134
2014	87.7792732166891
2015	87.78761061946902