|
| year | production | consumption |
| 1980 | | |
| 1981 | | |
| 1982 | 2.22 | 2.22 |
| 1983 | 2.12 | 2.12 |
| 1984 | 2.33 | 2.33 |
| 1985 | 2.19 | |
| 1986 | 3.00 | |
| 1987 | 3.43 | |
| 1988 | 4.10 | |
| 1989 | 4.13 | |
| 1990 | | |
| 1991 | | |
| 1992 | | |
| 1993 | 2.87 | 2.87 |
| 1994 | 1.34 | 1.34 |
| 1995 | 1.23 | 1.23 |
| 1996 | 1.34 | 1.48 |
| 1997 | 1.31 | 6.82 |
| 1998 | 1.17 | 30.41 |
| 1999 | .07 | 52.97 |
| 2000 | 1.27 | 72.47 |
| 2001 | 1.24 | 71.37 |
| 2002 | 1.31 | 76.63 |
| 2003 | .95 | 86.17 |
| 2004 | .88 | 94.79 |
| 2005 | .57 | 100.37 |
| 2006 | .81 | 116.96 |
| 2007 | .74 | 142.32 |
| 2008 | .49 | 148.61 |
| 2009 | .39 | 124.59 |
| 2010 | .25 | 135.96 |
| 2011 | .21 | 167.29 |
|
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