1998

6.1

1980

6.6

1984

7.1

1997

6.5

1983

7.4

2003

5.7

1979

5.8

1993

6.5

1991

6.6

2001

7.1

1996

5.5

2006

6.3

2008

5.7

2006

6.5

1970

7.5

1979

7.0

1993

6.0

2005

6.9

2006

7.6

1993

6.7