1975

6.3

2013

6.5

1999

6.8

1953

7.2

1986

6.2

2006

6.7

2017

6.9

2017

6.6

2005

6.9

2006

6.8

2014

6.3

1971

6.0

1965

6.4

2001

6.8

2020

6.7

1988

6.5

1933

6.2

1999

5.9

1988

5.7

1998

6.2