|
| year | production | change |
| 1980 | .54 | NA |
| 1981 | .56 | 3.24 % |
| 1982 | .56 | 1.03 % |
| 1983 | .50 | -10.35 % |
| 1984 | .54 | 6.58 % |
| 1985 | .56 | 4.15 % |
| 1986 | .54 | -2.87 % |
| 1987 | .51 | -5.85 % |
| 1988 | .45 | -11.11 % |
| 1989 | .43 | -6.20 % |
| 1990 | .41 | -5.05 % |
| 1991 | .38 | -5.08 % |
| 1992 | .37 | -3.84 % |
| 1993 | .43 | 14.98 % |
| 1994 | .44 | 3.22 % |
| 1995 | .44 | 0.64 % |
| 1996 | .43 | -3.28 % |
| 1997 | .40 | -7.09 % |
| 1998 | .40 | 1.37 % |
| 1999 | .39 | -3.10 % |
| 2000 | .39 | -0.72 % |
| 2001 | .40 | 3.16 % |
| 2002 | .40 | 0.94 % |
| 2003 | .40 | -0.32 % |
| 2004 | .41 | 1.31 % |
| 2005 | .47 | 15.96 % |
| 2006 | .51 | 7.00 % |
| 2007 | .54 | 6.63 % |
| 2008 | .59 | 9.14 % |
| 2009 | .62 | 5.92 % |
| 2010 | .81 | 29.81 % |
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