1984

6.8

2006

6.2

2002

6.2

2002

5.3

1998

5.8

2001

6.7

1996

6.0

1986

6.2

1938

5.2

1962

5.7

1944

3.5

1982

5.2

2008

6.0

1990

4.8

2008

6.4

2008

5.4

1933

8.4

1975

2.8

1974

6.5

1997

6.0