2007

6.9

2005

5.9

2006

6.2

2007

4.5

2003

5.3

2004

5.5

1979

5.5

2003

6.1

2001

7.9

1999

6.5

1979

6.7

2002

6.3

2004

5.8

1992

5.0

2011

5.3

2008

6.8

1998

5.8

1989

6.0

2014

5.2

2017

6.7