Year	% of total
1970	71.83515413516587
1971	72.02742122573285
1972	72.30052691605839
1973	71.20801586426242
1974	71.44022531549585
1975	72.88491841861749
1976	73.91914479583089
1977	74.53044299179311
1978	75.48128621373372
1979	76.28958490318776
1980	76.29250210587328
1981	75.34054195308343
1982	75.6968897620083
1983	79.93113362843881
1984	79.76910348397753
1985	80.87626004550754
1986	67.71879788218517
1987	74.48781256224083
1988	74.19897093756468
1989	74.18902702066747
1990	94.04096834264432
1991	93.8970588235294
1992	94.02570336922543
1993	93.97631133671743
1994	88.43663274745606
1995	89.03281519861831
1996	88.90481651376146
1997	89.05859483476813
1998	89.0106878596876
1999	89.20920391430839
2000	89.31061192873742
2001	89.3687707641196
2002	89.62006456419171
2003	89.87433542774286
2004	90.13589503280225
2005	90.61387900355872
2006	90.7682375726275
2007	90.6074967686342
2008	90.86786229643373