1990

7.2

1981

6.2

1970

8.2

2003

7.0

2008

7.6

2001

7.4

2020

6.0

1974

7.3

2011

6.5

1967

7.7

1995

6.2

1984

5.4

2007

6.4

1972

6.2

1952

6.7

2010

7.2

1920

7.9

1989

7.8

1970

7.5

2006

7.0