1993

5.6

2012

4.9

2009

4.8

2011

4.7

2010

7.5

2003

6.8

1991

0.0

2013

5.5

2006

5.0

1988

6.0

1986

0.0

2007

4.8

1994

7.4

1975

0.0

2006

5.9