1987

5.7

2007

6.3

1982

5.2

1993

6.2

1985

6.9

2012

9.3

2004

6.4

2003

6.7

2010

7.0

2013

5.5

1974

6.7

2009

5.6

2013

6.4

2004

4.8

2002

6.6

2008

5.7

1973

6.9

2014

4.9

2004

4.9

2015

6.5