|
| year | production | change |
| 1980 | .06 | NA |
| 1981 | .06 | 1.71 % |
| 1982 | .06 | -6.95 % |
| 1983 | .03 | -44.35 % |
| 1984 | .02 | -25.82 % |
| 1985 | .03 | 44.81 % |
| 1986 | .05 | 39.01 % |
| 1987 | .05 | 3.68 % |
| 1988 | .05 | 3.03 % |
| 1989 | .05 | 8.76 % |
| 1990 | .06 | 9.07 % |
| 1991 | .06 | 7.60 % |
| 1992 | .07 | 10.35 % |
| 1993 | .07 | -3.27 % |
| 1994 | .07 | -3.55 % |
| 1995 | .07 | 8.64 % |
| 1996 | .08 | 14.03 % |
| 1997 | .08 | -0.94 % |
| 1998 | .05 | -38.20 % |
| 1999 | .07 | 31.98 % |
| 2000 | .08 | 25.46 % |
| 2001 | .08 | 1.00 % |
| 2002 | .07 | -20.40 % |
| 2003 | .05 | -17.21 % |
| 2004 | .07 | 23.92 % |
| 2005 | .07 | 1.66 % |
| 2006 | .07 | -0.79 % |
| 2007 | .05 | -27.44 % |
| 2008 | .07 | 48.51 % |
| 2009 | .08 | 8.14 % |
| 2010 | .08 | 4.64 % |
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