1991

7.1

1997

7.2

1998

6.3

1994

5.2

2000

3.9

1991

4.8

1998

6.6

2005

8.1

1998

7.0

1995

4.7

1990

5.3

1989

8.3

1980

4.6

1990

6.9

1994

5.2