Year	% of total
1970	93.43382050468581
1971	93.18193276302283
1972	93.40220601453896
1973	93.3761297047458
1974	93.42268089838115
1975	93.49523767242589
1976	93.75416027914592
1977	93.66439427366294
1978	93.5726815001551
1979	93.39799273853706
1980	93.28563560037023
1981	93.09567546603412
1982	93.08449524510868
1983	93.14580792866738
1984	93.15511718997443
1985	93.08668626822967
1986	93.04493745831272
1987	93.20975561261267
1988	91.58984631726183
1989	90.10336871241816