1979

5.5

1975

6.2

1977

6.8

1988

6.1

1981

4.7

1981

6.5

1989

7.3

1984

5.7

1983

6.4

1984

7.1

1987

6.2

1986

7.1

1990

5.0

1997

6.5

1984

7.5

1976

7.5

1984

6.8

1991

6.3

1985

7.2

1981

7.3

1981

4.8

1983

7.5

1975

2.0

1998

5.9

1979

6.5