1975

6.7

1982

6.1

2008

6.1

1989

5.0

2009

6.5

1980

6.3

1979

6.7

2005

4.3

1976

4.8

1972

6.3

2002

6.1

1984

4.8

2006

6.5

2009

6.7

1983

7.2

1987

7.1

1976

7.7

2009

7.6

2000

7.0

2007

3.0