1981

6.8

1979

6.1

1966

7.1

1989

6.2

2005

6.9

1955

6.3

1969

7.4

1983

6.9

1944

7.6

1988

5.9

2000

7.3

1988

6.3

1994

6.5

1997

6.8

1962

7.9

1998

6.6

1991

5.9

1938

7.5

1993

4.8

2000

5.0