2005

6.8

2002

7.1

1970

6.3

1951

7.2

2001

6.9

2006

6.9

1994

8.9

1997

6.2

2000

6.5

2009

7.2

1994

7.6

2006

6.4

1986

7.0

1958

7.0

2009

6.6

1977

6.7

1974

8.6

1991

6.9

2003

7.0

1965

6.8