Year	%
1971	62.03106
1972	62.95564
1973	64.06412
1974	65.05059
1975	65.44301
1976	66.76118
1977	66.61693
1978	65.98369
1979	66.04501
1980	65.48867
1981	65.56594
1982	65.92177
1983	66.56868
1984	68.08567