1966

6.2

2007

5.4

1989

5.6

2013

6.2

1950

7.1

1966

6.7

2000

6.0

1940

7.0

2008

4.5

1977

6.8

2005

6.9

1949

5.9

1999

5.9

1949

6.9

1928

7.9

1988

6.5

1952

6.3

1985

7.2

2012

7.7

1984

8.0