1975     79.2    42.0    51.3    4883    44.0    49.0
  1976     84.2    39.3    51.3    5453    45.2    53.0
  1977     80.1    41.8    51.6    5941    48.9    56.8
  1978     75.0    61.1    59.9    6634    56.5    60.7
  1979     63.7    80.3    66.0    7408    63.9    65.8
  1980     63.1    87.2    71.0    8281    70.8    71.4
  1981     64.8    89.5    84.5    9545    78.9    78.8
  1982     64.2    88.9    86.8   10430    84.6    86.3
  1983     63.9    89.6    89.9   10843    87.7    90.7
  1984     60.9    95.5    95.8   11686    92.6    93.9
  1985     61.7    97.9    91.8   12387    95.2    97.0
  1986     61.2   100.0   100.0   12902   100.0   100.0
  1987     58.2   109.1   106.1   13613   104.4   103.9
  1988     58.2   110.8   107.6   14658   107.2   107.7
  1989     56.6   113.2   120.0   15783   111.1   112.5
  1990     54.5   117.6   126.1   16263   115.7   116.6
  1991     53.4   118.3   123.5   16570   121.2   119.9
  1992     51.7   116.8   123.0   16753   120.8   121.4
  1993     49.6   123.1   125.6   16874   122.8   123.0
  1994     50.6   124.1   119.3   17003   123.3   123.9