1973

5.2

1981

6.5

1988

5.8

1988

4.7

2005

6.7

1978

0.0

1979

6.8

2005

6.6

1977

6.0

1991

5.1

1997

6.0

1991

6.6

1998

0.0

1982

7.1

1985

7.3

1989

6.0

1990

7.0

2004

3.5