1967

5.5

2005

6.5

1976

6.6

2008

6.8

1988

7.4

2008

6.1

1995

6.5

2004

6.0

2006

7.4

1990

6.1

1999

6.6

2001

4.8

1998

6.2

1980

5.6

2003

6.5

1986

7.0

1993

6.2

1990

6.4

1990

6.7

1996

5.5