1984

7.0

1993

8.2

1992

6.5

1986

6.7

2006

4.5

1997

5.6

1979

7.1

1995

8.1

1968

6.0

1978

7.7

1996

8.1

2007

0.0

1979

7.2

1995

6.4

1987

6.3

2003

7.7

1976

7.5

2006

5.0

1990

7.9

2004

8.5