1992

6.8

2000

6.1

1964

7.0

1973

3.3

2006

6.5

1983

6.7

1972

3.8

1991

4.5

1972

4.0

2006

6.5

1997

4.3

1995

6.5

2008

6.6

2009

5.8

1944

6.7

1995

6.3

1963

6.2

2007

5.7

1993

6.4

1971

4.0