1998

7.2

1987

6.4

1990

7.3

1980

6.3

1975

7.5

1950

7.7

1947

6.7

1990

5.0

1961

6.5

1989

6.2

1991

6.9

1943

6.9

1939

6.9

1981

6.0

1988

6.2

2002

0.0

1964

7.0

1948

0.0

1945

6.9

1935

6.3