1997

7.4

1971

8.2

1983

7.2

1986

7.8

1972

8.7

1974

8.6

2005

6.7

1959

7.8

2000

7.3

1994

6.3

2006

5.5

1992

6.7

2002

7.0

2002

6.2

1964

5.7

1995

6.5

1954

6.4

2002

6.3

1992

5.5

1997

6.4