1960   15.863
1961   16.412
1962   16.951
1963   17.530
1964   18.026
1965   18.464
1966   18.831
1967   19.175
1968   19.432
1969   19.745
1970   20.039
1971   20.346
1972   20.585
1973   20.869
1974   21.174
1975   21.538
1976   21.936
1977   22.352
1978   22.836
1979   23.257
1980   23.782
1981   24.278
1982   24.805
1983   25.337
1984   25.816
1985   26.403
1986   27.052
1987   27.717
1988   28.393
1989   29.142
1990   29.976
1991   30.655
1992   31.306
1993   31.746
1994   32.140