|
| year | production | consumption |
| 1984 | | |
| 1985 | | |
| 1986 | 2.51 | 2.29 |
| 1987 | 2.66 | 2.58 |
| 1988 | 3.14 | 2.87 |
| 1989 | 3.39 | 2.88 |
| 1990 | 3.65 | 3.44 |
| 1991 | 2.78 | 2.55 |
| 1992 | 3.38 | 3.17 |
| 1993 | 2.80 | 2.57 |
| 1994 | 2.69 | 2.45 |
| 1995 | 2.73 | 2.50 |
| 1996 | 2.80 | 2.56 |
| 1997 | 2.80 | 2.57 |
| 1998 | 2.80 | 2.57 |
| 1999 | 1.10 | 2.64 |
| 2000 | .14 | 3.10 |
| 2001 | 2.17 | 3.23 |
| 2002 | 2.34 | 3.39 |
| 2003 | 2.57 | 3.51 |
| 2004 | 2.75 | 3.66 |
| 2005 | 2.94 | 3.83 |
| 2006 | 2.94 | 4.02 |
| 2007 | 3.32 | 4.30 |
| 2008 | 2.43 | 3.01 |
| 2009 | 2.59 | 3.20 |
| 2010 | 3.20 | 3.67 |
|
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