1951

6.1

1993

6.4

1998

6.9

1968

7.0

2000

5.6

1944

6.7

1954

6.9

1942

7.1

1954

7.1

1994

7.3

2005

9.0

2007

6.7

1933

6.9

1981

6.4

2001

7.6

2006

7.5

2002

7.1

2007

7.4

1987

5.4

1984

6.5