1992

6.2

1982

6.7

1975

6.3

1994

6.5

1971

7.2

2001

7.8

1966

7.3

1999

7.0

1999

7.1

1982

8.1

1999

7.2

2006

6.3

2007

6.5

1991

6.2

1993

6.3

2002

5.7

1999

6.8

1997

7.8

1960

7.3

1997

6.9