1954

6.4

1955

7.9

2000

5.0

1995

6.5

1994

6.3

1991

8.3

2003

6.5

1984

8.4

2003

7.7

2005

7.0

1997

7.4

1971

8.2

1983

7.2

1986

7.8

1972

8.7

1974

8.6

2005

6.7

1971

7.1

2000

7.4

1967

7.7