1991

6.3

1998

7.0

1992

6.0

1994

3.9

2000

6.2

1998

6.2

2006

7.0

1991

6.3

1997

3.5

2000

7.3

1996

6.5

1996

4.5

2002

5.3

2003

7.3

1996

6.2

2005

8.3

1985

7.2

1996

7.1

1993

8.4

1988

6.2