Year % 1970 55.06254 1971 69.46805 1972 88.50478 1973 88.41413 1974 88.84941 1975 89.01631 1976 92.72167 1977 92.7657 1978 92.12849 1979 93.76834 1980 89.00044 1981 94.4668 1983 89.84488 1984 91.96418 1991 100 1992 99.08433 1993 95.70886 2000 97.87674 2001 97.90624 2002 96.90012 2003 95.21936