1949 1952 1957 1960 1965 1970 1975 1980 1985 1986 1987 1988 1989 1990 1991 1992 1993 | 64.8 76.4 89.6 93.2 92.3 90.6 91.4 88.2 79.5 79.1 79.0 79.5 79.5 79.6 79.8 80.1 80.3 | 12.9 14.9 21.6 23.2 20.9 20.6 23.4 23.8 24.4 24.8 25.4 25.7 26.0 26.0 26.4 26.9 27.5 | 51.9 61.5 68.0 70.0 71.4 70.0 68.0 64.4 55.1 54.3 53.6 53.8 53.5 53.6 53.4 53.2 52.8 | 8.11 8.04 7.49 6.56 6.10 4.90 4.18 3.60 2.88 2.80 2.73 2.69 2.62 2.56 2.52 2.49 2.45 |