1980

6.7

1999

6.8

1966

8.2

2006

5.6

1998

6.6

2001

7.4

1993

5.5

2005

7.0

2004

7.2

1995

7.0

2006

7.0

1999

7.5

1990

7.5

1957

8.5

2000

7.0

1984

3.3

1990

5.7

2013

5.4

1969

6.2

2003

6.4