1991

0.0

1977

6.2

1986

7.4

1979

6.5

1982

6.5

1985

7.2

1981

7.5

1980

5.8

1984

6.2

1976

4.2

1975

6.9

1976

7.3

1987

6.1

1979

7.9

1988

0.0

1983

6.4