1970

5.6

1991

9.3

2001

6.8

1995

6.5

2003

7.2

2005

6.6

1999

6.6

2002

6.5

2007

7.2

2003

6.5

1998

7.5

1992

6.6

2002

7.0

1983

7.4

2002

7.0

1993

7.5

1993

7.3

2002

6.2

1996

6.9

2002

6.6