|
| year | production | consumption |
| 1980 | | 5.51 |
| 1981 | | 4.41 |
| 1982 | | 3.31 |
| 1983 | | 2.20 |
| 1984 | | 2.20 |
| 1985 | | 1.10 |
| 1986 | | 1.10 |
| 1987 | | 1.10 |
| 1988 | | 1.10 |
| 1989 | | 1.10 |
| 1990 | | 1.10 |
| 1991 | | .55 |
| 1992 | | .44 |
| 1993 | | 2.29 |
| 1994 | | 4.54 |
| 1995 | | 3.64 |
| 1996 | | 1.27 |
| 1997 | | 1.28 |
| 1998 | | 1.28 |
| 1999 | | 1.94 |
| 2000 | | .79 |
| 2001 | | 1.60 |
| 2002 | | 2.56 |
| 2003 | | 1.93 |
| 2004 | | 2.36 |
| 2005 | | 3.04 |
| 2006 | | 3.51 |
| 2007 | | 4.30 |
| 2008 | | 2.60 |
| 2009 | | 3.01 |
| 2010 | | 4.74 |
| 2011 | | 2.84 |
|
|
