1977

6.8

1971

8.1

1980

5.0

1976

5.7

1972

7.8

1980

6.3

1985

6.5

1978

6.7

1982

5.0

1992

3.3

1968

4.0

1987

5.7

1986

6.6

1984

7.4

1981

2.5

1986

5.0

1995

6.2

1969

3.5

1984

5.6

1979

3.7