2005

6.8

2007

6.6

1995

7.3

1990

7.0

1955

6.0

1985

6.7

1989

7.0

1992

6.7

1998

6.6

2007

6.7

1978

6.0

1987

4.1

1997

4.5

1994

6.7

2005

6.3

2000

5.5

1995

5.2

1988

6.4

1983

6.5

2004

5.0