Year	% of total
1970	96.5322575791278
1971	95.55410162406065
1972	95.29855826167551
1973	95.14637372346232
1974	94.06751005667121
1975	93.80125320943229
1976	91.94054689619826
1977	91.77836307026153
1978	92.07906008129913
1979	92.01019036798058
1980	91.40295389885037
1981	91.22579153839575
1982	90.32092023757046
1983	90.92134156836532
1984	90.73494623799395
1985	90.26839583404944
1986	90.09933827469067
1987	89.86484667103515
1988	90.13747519398565
1989	85.54252250426762