2005

4.7

1990

6.9

1998

7.3

2012

6.6

2015

6.9

1997

6.3

2016

7.2

1983

8.1

2017

7.9

2010

7.8

2017

7.0

2007

7.3

2004

8.0

1973

8.1

2014

8.4

2008

7.7

1996

7.1

2011

8.5

2009

7.3

2015

8.1