|
| year | production | change |
| 1980 | 28.00 | NA |
| 1981 | 25.00 | -10.71 % |
| 1982 | 26.00 | 4.00 % |
| 1983 | 25.00 | -3.85 % |
| 1984 | 23.00 | -8.00 % |
| 1985 | 22.00 | -4.35 % |
| 1986 | 22.00 | 0.00 % |
| 1987 | 21.00 | -4.55 % |
| 1988 | 23.00 | 9.52 % |
| 1989 | 23.00 | 0.00 % |
| 1990 | 22.00 | -4.35 % |
| 1991 | 25.50 | 15.91 % |
| 1992 | 22.85 | -10.39 % |
| 1993 | 21.69 | -5.08 % |
| 1994 | 21.34 | -1.61 % |
| 1995 | 22.90 | 7.31 % |
| 1996 | 21.50 | -6.14 % |
| 1997 | 19.00 | -11.62 % |
| 1998 | 20.50 | 7.92 % |
| 1999 | 18.00 | -12.21 % |
| 2000 | 19.00 | 5.56 % |
| 2001 | 18.67 | -1.74 % |
| 2002 | 18.58 | -0.47 % |
| 2003 | 17.92 | -3.58 % |
| 2004 | 18.08 | 0.92 % |
| 2005 | 16.82 | -6.98 % |
| 2006 | 16.75 | -0.37 % |
| 2007 | 16.75 | -0.03 % |
| 2008 | 16.08 | -3.98 % |
| 2009 | 16.32 | 1.47 % |
| 2010 | 16.75 | 2.62 % |
| 2011 | 17.66 | 5.46 % |
| 2012 | 16.92 | -4.22 % |
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