1983

5.4

1981

5.5

1990

4.9

1988

5.3

1985

4.5

1980

6.4

1989

8.0

1978

4.9

1983

4.7

1992

5.9

1994

6.8

1989

5.6

1992

4.1

1989

4.5

1987

6.5

1982

6.2

1979

6.7