1972

6.3

1987

7.4

1991

6.4

1992

5.4

2001

7.2

2000

7.6

2000

7.0

1994

7.8

1999

8.2

2002

8.3

2007

7.3

2003

7.2

1999

7.5

2001

6.8

1999

6.8

1988

4.9

1999

9.5

2002

8.1

1997

4.5