1991

8.1

2006

7.1

2003

7.2

2010

7.5

2008

7.6

2006

8.6

1957

7.7

2009

7.7

1976

8.5

2006

8.6

1992

8.2

2001

8.6

2005

8.6

1999

7.9

2016

7.3

2015

7.7

2005

7.9

2016

8.6

2020

7.4

2016

7.5