1999

6.4

1985

6.7

1988

7.1

2005

7.7

2007

6.7

2002

7.6

1999

6.1

1995

6.7

1975

7.3

2004

8.2

2001

7.8

2005

7.9

2000

8.0

1985

8.3

9.2

1987

8.2

1960

7.4

2003

6.2

1988

7.7

1999

7.7