|
| year | production | change |
| 1980 | .04 | NA |
| 1981 | .04 | -7.35 % |
| 1982 | .04 | -9.91 % |
| 1983 | .04 | -0.76 % |
| 1984 | .04 | 1.16 % |
| 1985 | .04 | 0.06 % |
| 1986 | .04 | 1.65 % |
| 1987 | .03 | -10.22 % |
| 1988 | .03 | 3.43 % |
| 1989 | .03 | -6.72 % |
| 1990 | .03 | 3.17 % |
| 1991 | .03 | 2.18 % |
| 1992 | .03 | -8.67 % |
| 1993 | .03 | -13.97 % |
| 1994 | .03 | 21.29 % |
| 1995 | .03 | -7.86 % |
| 1996 | .04 | 30.88 % |
| 1997 | .04 | -6.91 % |
| 1998 | .03 | -18.65 % |
| 1999 | .02 | -37.93 % |
| 2000 | .01 | -32.37 % |
| 2001 | .01 | 14.00 % |
| 2002 | .01 | -6.58 % |
| 2003 | .02 | 47.72 % |
| 2004 | .02 | 8.80 % |
| 2005 | .01 | -28.15 % |
| 2006 | .01 | 0.33 % |
| 2007 | .01 | -5.87 % |
| 2008 | .02 | 8.37 % |
| 2009 | .03 | 108.77 % |
| 2010 | .04 | 35.42 % |
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