1997

4.5

1997

5.4

2001

1.0

2006

5.2

2006

4.1

2007

6.0

2012

5.9

2011

6.7

2005

2.4

2010

2.8

2011

6.1

1970

6.2

2015

0.0

2008

7.0

2003

0.0

1999

6.8

2009

7.0