1968

6.6

1990

6.1

1986

6.8

1998

6.0

2009

5.4

1948

7.3

1953

6.8

1987

7.5

2001

6.4

2009

4.8

2006

7.0

1982

6.2

1928

7.3

1985

6.2

1992

7.4

2010

5.8

2008

5.9

1961

7.3

1945

7.4

2005

6.4