1980

3.4

1981

4.1

1983

7.0

1979

5.3

1999

4.0

1997

4.0

1989

5.2

2000

3.0

1991

5.2

1992

4.7

1999

4.1

2000

4.4

2000

5.2

1974

3.8

1971

6.0

1990

3.5

1976

0.0

1972

4.0

2005

3.6

1980

4.8