1990

6.6

1991

6.4

1982

6.8

1994

6.2

1987

7.3

1993

8.0

2000

7.0

1994

5.2

1999

6.8

1988

7.8

1996

7.6

1998

6.1

1984

6.9

1987

6.3

1992

5.3

1997

7.0

1985

6.7