|
| year | production | change |
| 1980 | .02 | NA |
| 1981 | .02 | 8.44 % |
| 1982 | .02 | 4.49 % |
| 1983 | .03 | 19.52 % |
| 1984 | .03 | 5.39 % |
| 1985 | .03 | -7.65 % |
| 1986 | .03 | 4.25 % |
| 1987 | .03 | 3.51 % |
| 1988 | .03 | 0.61 % |
| 1989 | .03 | 9.97 % |
| 1990 | .03 | 1.57 % |
| 1991 | .04 | 8.73 % |
| 1992 | .04 | 9.77 % |
| 1993 | .05 | 8.83 % |
| 1994 | .05 | -0.24 % |
| 1995 | .04 | -8.53 % |
| 1996 | .04 | 7.99 % |
| 1997 | .06 | 23.62 % |
| 1998 | .05 | -9.27 % |
| 1999 | .06 | 22.56 % |
| 2000 | .07 | 13.09 % |
| 2001 | .07 | 1.15 % |
| 2002 | .07 | 5.99 % |
| 2003 | .07 | -1.62 % |
| 2004 | .08 | 8.32 % |
| 2005 | .08 | -0.21 % |
| 2006 | .08 | 1.49 % |
| 2007 | .08 | 1.70 % |
| 2008 | .09 | 5.38 % |
| 2009 | .09 | -0.21 % |
| 2010 | .09 | 0.91 % |
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