1975

6.7

2005

10.0

2016

8.6

1997

8.1

2013

8.2

2006

8.6

2017

8.0

2015

7.6

2010

7.7

2014

7.3

2011

7.6

1969

7.8

2005

7.6

2015

8.3

2014

7.8

2010

7.8

2016

7.6

2008

7.4

2005

8.1

1989

8.4