1960    3.53   312.3    -0.3
1961    3.00   335.5     3.3
1962    3.00   362.7     7.1
1963    3.23   393.2     4.8
1964    3.55   424.8     5.9
1965    4.04   459.3     1.4
1966    4.50   480.0     3.7
1967    4.19   524.3     8.6
1968    5.16   566.3    25.2
1969    5.87   589.5    -3.2
1970    5.95   628.1     2.8
1971    4.88   712.7    23.0
1972    4.50   805.2    23.4
1973    6.44   861.0    14.9
1974    7.83   908.5     6.1
1975    6.25  1023.2    53.2
1976    5.50  1163.7    73.7
1977    5.46  1286.5    53.7
1978    7.46  1388.6    59.2
1979   10.28  1496.9    40.7
1980   11.77  1629.3    73.8
1981   13.42  1793.3    79.0
1982   11.02  1953.2   128.0
1983    8.50  2187.7   207.8
1984    8.80  2378.4   185.4
1985    7.69  2576.0   212.3
1986    6.33  2820.3   221.2
1987    5.66  2922.3   149.8
1988    6.20  3083.5   155.2
1989    6.93  3243.0   152.5
1990    6.98  3356.0   221.4
1991    5.45  3457.9   269.2
1992    3.25  3515.3   290.4
1993    3.00  3583.6   255.1
1994    3.60  3617.0   203.2
1995    5.21  3780.7   163.8