|
| year | production | consumption |
| 1980 | | 7.90 |
| 1981 | | 9.20 |
| 1982 | | 9.10 |
| 1983 | | 8.90 |
| 1984 | | 9.20 |
| 1985 | | 9.08 |
| 1986 | | 9.63 |
| 1987 | | 7.18 |
| 1988 | | 7.27 |
| 1989 | | 7.40 |
| 1990 | | 6.75 |
| 1991 | | 4.03 |
| 1992 | | 3.74 |
| 1993 | | 3.86 |
| 1994 | | 3.86 |
| 1995 | | 3.86 |
| 1996 | | 3.86 |
| 1997 | | 3.86 |
| 1998 | | 3.86 |
| 1999 | | 3.86 |
| 2000 | | 4.80 |
| 2001 | | 4.80 |
| 2002 | | 4.80 |
| 2003 | | 4.80 |
| 2004 | | 4.80 |
| 2005 | | 4.86 |
| 2006 | | 5.11 |
| 2007 | | 5.76 |
| 2008 | | 5.46 |
| 2009 | | 5.40 |
| 2010 | | 5.40 |
| 2011 | | |
|
|