1992

6.3

2002

6.7

1997

6.4

1975

6.8

2002

6.5

2009

7.6

2002

5.6

2007

6.9

1956

7.1

2007

6.7

2002

5.3

2000

6.5

1972

7.7

1971

7.5

1985

6.4

2001

5.9

1986

5.8

1999

6.8

2001

6.9

1978

7.2