1947

7.6

1987

6.5

1986

7.6

1995

8.4

1958

7.5

1951

7.7

2001

7.8

1993

7.4

2006

6.1

2006

6.0

2001

6.1

2005

5.4

1995

6.5

1990

6.7

1929

6.5

1992

6.9

1958

8.2

2002

5.5

1971

6.8

1954

8.0