1950

8.0

1961

7.6

1974

7.8

1940

7.9

1971

7.6

2001

7.3

1976

7.0

1992

4.4

2005

6.0

2004

6.1

2001

6.9

1972

6.3

1983

5.0

2008

7.5

2009

5.9

2002

5.9

1954

7.3

1999

4.2

2007

5.9

1981

6.0