1959     5.2    29.1    0.69     4.9
1960     5.4    29.6    1.72     2.4
1961     6.4    29.9    1.01     2.4
1962     5.2    30.2    1.00     4.0
1963     5.7    30.6    1.32     3.0
1964     5.2    31.0    1.31     3.2
1965     4.5    31.5    1.61     4.5
1966     3.8    32.4    2.86     3.5
1967     3.8    33.4    3.09     3.1
1968     3.6    34.8    4.19     5.8
1969     3.5    36.7    5.46     6.4
1970     4.9    38.8    5.72     4.6
1971     5.9    40.5    4.38     6.2
1972     5.6    41.8    3.21     7.5
1973     4.9    44.4    6.22     6.2
1974     5.6    49.3   11.04     6.4
1975     8.5    53.8    9.13     5.7
1976     7.7    56.9    5.76     7.3
1977     7.1    60.6    6.50     7.7
1978     6.1    65.2    7.59     7.8
1979     5.8    72.6   11.35     8.0
1980     7.1    82.4   13.50     6.9
1981     7.6    90.9   10.32     8.5
1982     9.7    96.5    6.16     4.7
1983     9.6    99.6    3.21     5.0
1984     7.5   103.9    4.32     4.3
1985     7.2   107.6    3.56     2.1
1986     7.0   109.6    1.86     1.9
1987     6.2   113.6    3.65     2.5
1988     5.5   118.3    4.14     3.0
1989     5.3   124.0    4.82     3.8
1990     5.5   130.7    5.40     3.3
1991     6.7   136.2    4.21     2.5
1992     7.4   140.3    3.01     2.7
1993     6.8   144.5    2.99     2.8
1994     6.1   148.2    2.56     3.4
1995     5.6   152.4    2.83     2.4