1961    41.400    45.03512
1962    51.800    50.05673
1963    44.300    44.30000
1964    48.000    44.54000
1965    44.826    59.97878
1966    39.208    45.37687
1967    48.278    46.60833
1968    37.819    52.24526
1969    31.992    54.11967
1970    29.894    35.60816
1971    39.406    61.24754
1972    34.279    54.76161
1973    27.958    46.56643
1974    36.407    28.51477
1975    27.827    27.16532
1976    33.710    38.83327
1977    32.888    22.07106
1978    35.804    31.36205
1979    38.950    25.68735
1980    29.157    19.38004
1981    23.748    21.78884
1982    28.333    20.10470
1983    31.945    27.18085
1984    18.434    17.92367
1985    22.531    18.97028
1986    25.587    22.37778
1987    29.777    16.89844
1988    27.906    20.19613
1989    25.757    16.42839
1990    24.503    15.57284
1991    16.608    17.14402
1992    18.162    15.78574
1993    18.371    12.12064
1994    16.993    10.31185