1997

5.1

2010

6.8

2009

7.5

2001

5.2

1993

6.2

1977

5.9

1945

6.0

1956

6.1

2001

8.9

2007

6.9

2012

6.9

1977

6.7

2013

7.1

1991

6.7

2004

5.9

1991

7.0

2016

6.8

2016

7.4

1994

6.5

1998

5.1