1979

8.3

2003

7.4

2006

6.3

1992

7.0

1988

8.4

1983

6.2

1999

6.5

1992

6.6

2006

4.2

1973

4.3

1987

6.7

2002

7.0

2006

6.3

1999

7.5

1989

7.5

1995

6.7

2002

6.6

2005

6.3

1990

5.4

2012

10.0