|
| year | production | consumption |
| 1980 | 3.94 | 1.58 |
| 1981 | 3.29 | 1.49 |
| 1982 | 5.14 | 1.71 |
| 1983 | 5.68 | 2.09 |
| 1984 | 5.30 | 2.23 |
| 1985 | 5.59 | 2.40 |
| 1986 | 5.06 | 2.43 |
| 1987 | 5.67 | 2.54 |
| 1988 | 5.71 | 2.70 |
| 1989 | 7.02 | 2.98 |
| 1990 | 7.67 | 3.10 |
| 1991 | 8.27 | 3.24 |
| 1992 | 8.53 | 3.36 |
| 1993 | 8.83 | 3.23 |
| 1994 | 9.16 | 3.69 |
| 1995 | 9.35 | 3.83 |
| 1996 | 9.65 | 3.96 |
| 1997 | 9.84 | 4.43 |
| 1998 | 9.90 | 4.58 |
| 1999 | 10.00 | 4.84 |
| 2000 | 10.40 | 5.02 |
| 2001 | 10.67 | 5.39 |
| 2002 | 10.44 | 5.89 |
| 2003 | 11.36 | 6.19 |
| 2004 | 12.06 | 6.41 |
| 2005 | 13.12 | 7.34 |
| 2006 | 13.12 | 7.68 |
| 2007 | 13.00 | 7.90 |
| 2008 | 13.36 | 8.10 |
| 2009 | 14.26 | 9.04 |
| 2010 | 14.61 | 9.11 |
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