1973

7.5

2004

5.7

2009

5.3

1966

6.5

2016

5.0

1993

5.4

2012

6.2

2016

8.1

2002

6.9

1999

5.8

1996

5.4

2010

4.7

2005

6.2

2008

7.7

2011

4.9

1988

6.1

2007

7.7

1993

5.5

1976

7.5

2013

6.7