|
| year | production | consumption |
| 1980 | | 3.30 |
| 1981 | | 3.70 |
| 1982 | | 3.30 |
| 1983 | | 2.60 |
| 1984 | | 2.40 |
| 1985 | | 5.50 |
| 1986 | | 8.23 |
| 1987 | | 8.40 |
| 1988 | | 10.84 |
| 1989 | | 9.33 |
| 1990 | | 9.69 |
| 1991 | | 9.98 |
| 1992 | | 17.64 |
| 1993 | | 18.35 |
| 1994 | | 18.45 |
| 1995 | | 18.49 |
| 1996 | | 18.52 |
| 1997 | | 18.50 |
| 1998 | | 21.45 |
| 1999 | | 18.59 |
| 2000 | | 41.09 |
| 2001 | | 22.68 |
| 2002 | | 23.07 |
| 2003 | | 23.67 |
| 2004 | | 24.35 |
| 2005 | | 25.05 |
| 2006 | | 25.61 |
| 2007 | | 26.40 |
| 2008 | | 27.00 |
| 2009 | | 27.79 |
| 2010 | | 28.23 |
| 2011 | | 18.00 |
|
|