1957

7.4

1955

3.3

1975

5.2

1974

7.2

1985

6.6

1982

7.6

1971

8.1

1974

6.1

1981

6.2

1963

5.3

1974

6.0

1979

6.0

1960

6.4

1952

6.3

1962

6.0

1953

5.7

1965

6.1

1968

6.7

1954

6.9

1969

5.5

1979

6.7

1965

5.7

1948

6.4

1963

6.2

1960

6.1

1974

6.4