1997

6.3

1998

6.1

2004

6.6

2003

4.8

1967

6.5

1998

6.0

2009

5.7

6.4

2006

6.3

1961

6.9

2015

6.3

2010

6.7

2003

6.6

2006

6.7

1970

8.2

2013

5.5

2008

6.8

2010

6.8

1989

5.8

1993

7.5