1990

6.4

1999

6.5

1986

7.5

1990

7.4

1993

7.3

1988

5.6

1990

5.3

1989

6.3

1987

7.1

1981

5.0

1995

6.2

1987

6.2

1991

6.8

2000

6.5

1991

5.4

1987

6.6

2001

6.6

1984

7.5

1987

6.5

1999

6.7