2009

15.6c

21.0c

2008

21.6c

20.5c

2007

19.4c

20.0c

2006

22.2c

39.6c

2005

21.3c

18.2c

2004

18.6c

16.5c

2003

16.9c

14.8c

2002

14.1c

14.8c

2001

15.1c

14.4c

2000

14.5c

13.3c

1999

13.5c

12.5c

1998

11.6c

9.5c

1997

10.1c

6.8c

1996

9.8c

6.2c

1995

8.7c

5.7c

1994

7.1c

5.3c

1993

6.3c

5.1c

1992

5.9c

4.9c

1991

7.0c

4.7c

1990

7.9c

4.5c

1989

8.3c

5.1c

1988

3.8c

2.7c

1987

2.4c

2.0c

1986

2.0c

1.7c