1980

6.1

2004

7.7

2017

7.3

2011

5.2

1978

7.6

2013

5.8

2006

6.4

2012

6.1

2011

6.2

1997

6.6

1994

7.5

2012

7.0

2014

7.4

2015

6.8

2015

7.5

2010

7.2

2016

7.0

2014

7.9

2003

7.8

1985

7.7