1961  113.4
1962  129.6
1963  140.4
1964  153.2
1965  170.2
1966  181.6
1967  193.6
1968  211.1
1969  233.3
1970  264.1
1971  304.3
1972  341.0
1973  386.5
1974  444.8
1975  509.1
1976  546.2
1977  582.7
1978  620.8
1979  669.8
1980  722.4
1981  766.2
1982  796.0
1983  816.4
1984  849.0
1985  875.5
1986  912.3
1987  949.6
1988  991.1
1989 1018.9
1990 1118.1