1979

5.3

1970

5.2

1976

5.4

1984

6.1

1980

5.4

1981

7.6

1975

6.8

1976

6.1

1982

3.1

1972

6.3

1977

6.2

1971

5.0

1981

5.0

1972

6.8

1973

6.6

1983

7.3

1986

6.5