|
| year | production | change |
| 1980 | .48 | NA |
| 1981 | .52 | 8.38 % |
| 1982 | .52 | 1.36 % |
| 1983 | .52 | -0.33 % |
| 1984 | .49 | -5.81 % |
| 1985 | .55 | 11.95 % |
| 1986 | .56 | 1.83 % |
| 1987 | .58 | 3.88 % |
| 1988 | .60 | 3.29 % |
| 1989 | .54 | -9.64 % |
| 1990 | .55 | 2.17 % |
| 1991 | .57 | 2.66 % |
| 1992 | .58 | 1.91 % |
| 1993 | .61 | 5.04 % |
| 1994 | .65 | 7.46 % |
| 1995 | .61 | -6.20 % |
| 1996 | .55 | -10.02 % |
| 1997 | .61 | 9.89 % |
| 1998 | .61 | -0.17 % |
| 1999 | .67 | 11.31 % |
| 2000 | .65 | -3.83 % |
| 2001 | .70 | 8.53 % |
| 2002 | .64 | -9.03 % |
| 2003 | .64 | 0.18 % |
| 2004 | .62 | -3.57 % |
| 2005 | .56 | -9.68 % |
| 2006 | .60 | 7.30 % |
| 2007 | .64 | 6.95 % |
| 2008 | .65 | 0.83 % |
| 2009 | .64 | -1.04 % |
| 2010 | .63 | -1.42 % |
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