1975

8.2

1984

7.7

1993

6.0

1978

7.1

1978

7.2

2005

7.0

2003

4.2

2005

7.0

1997

7.6

1974

8.1

2006

6.8

1995

7.1

1995

7.1

1968

7.1

1996

6.8

2005

7.7

2001

7.7

1999

7.3

1998

10.0

1993

8.1