1997

6.7

2000

7.1

2005

5.6

1998

7.1

2001

6.0

1983

6.2

2007

6.7

1996

7.2

2002

6.6

2000

6.7

1995

6.3

1984

6.4

1993

6.8

1985

7.1

1992

6.1

2000

6.1

1998

7.1

2001

6.8

1960

7.6

1998

7.2