1980

6.1

1993

6.5

1968

6.0

1956

6.5

2000

5.9

1980

6.8

1964

8.2

2004

6.1

1999

5.9

1995

4.6

1974

7.3

1970

7.6

1967

6.9

1949

8.0

1994

5.8

1988

6.5

1976

7.0

1979

7.7

1932

7.4

1984

6.5