1971

5.2

1994

2.0

1977

2.0

1996

4.6

1997

4.7

2005

5.8

1999

5.3

1976

4.8

2002

5.3

1976

3.3

2009

6.6

1995

2.0

2000

5.6

1993

6.3

1979

6.0

1988

2.0

2003

7.8

1976

0.0

1970

4.1

2012

2.3