1960    84.5    57.94
1961    88.2    60.59
1962    90.4    64.44
1963    91.1    70.66
1964    93.2    76.83
1965   100.4    80.00
1966    93.5    84.82
1967    93.0    86.84
1968    98.7    88.81
1969   104.4    88.28
1970   109.4    85.29
1971   111.1    83.18
1972   105.3    85.07
1973   109.6    86.72
1974   107.4    85.45
1975   108.0    83.41
1976   110.0    87.44
1977   109.0    90.11
1978   109.3    94.50
1979   108.9    99.28
1980   113.0   103.64
1981   114.5   108.77
1982   118.4   113.96
1983   112.4   121.72
1984   120.6   133.33
1985   127.1   144.78
1986   133.0   148.39
1987   139.8   150.90
1988   151.9   154.36
1989   166.3   157.19
1990   176.7   161.86
1991   178.4   164.54
1992   187.2   166.70
1993   189.4   165.20