1991

8.1

2003

6.2

2006

6.0

2000

7.4

1991

4.1

1983

6.1

1990

7.3

1988

7.8

1999

8.2

2003

7.1

1997

6.8

2008

6.6

2007

6.1

2007

6.6

1995

7.3

1990

7.0

1987

7.3

1989

7.0

1992

6.7

1998

6.6