1970

5.6

1967

5.5

1991

9.3

2003

6.8

2000

6.0

1995

6.5

1994

8.3

2003

7.2

1999

6.6

2007

7.2

1980

5.6

1998

7.5

1992

6.6

2002

7.0

1990

6.1

1983

7.4

1990

6.7

2002

6.2

2002

6.6

1996

5.4