|
| year | production | consumption |
| 1980 | | 4.20 |
| 1981 | | |
| 1982 | | |
| 1983 | | |
| 1984 | | |
| 1985 | | |
| 1986 | | 3.43 |
| 1987 | | 4.69 |
| 1988 | | 6.15 |
| 1989 | | 7.17 |
| 1990 | | 6.25 |
| 1991 | | 6.60 |
| 1992 | | 21.95 |
| 1993 | | 22.58 |
| 1994 | | 22.51 |
| 1995 | | 22.81 |
| 1996 | | 22.95 |
| 1997 | | 23.15 |
| 1998 | | 23.25 |
| 1999 | | 23.25 |
| 2000 | | 23.76 |
| 2001 | | 23.74 |
| 2002 | | 22.75 |
| 2003 | | 23.30 |
| 2004 | | 19.96 |
| 2005 | | 23.52 |
| 2006 | 30.62 | 20.61 |
| 2007 | 14.99 | 18.70 |
| 2008 | 12.83 | 12.88 |
| 2009 | 11.25 | 12.81 |
| 2010 | 8.23 | 12.81 |
| 2011 | 7.74 | 21.00 |
|
|