1993

5.1

2000

4.4

1984

6.1

1989

6.8

1989

2.7

1979

6.9

1988

6.5

1989

8.0

1992

6.7

1989

5.2

1996

7.1

1987

6.4

1990

7.4

1984

6.2

2004

7.8