|
| year | production | consumption |
| 1980 | | |
| 1981 | | |
| 1982 | | |
| 1983 | | |
| 1984 | | |
| 1985 | | 1.08 |
| 1986 | | 1.08 |
| 1987 | | 1.08 |
| 1988 | | .75 |
| 1989 | | 1.08 |
| 1990 | | 1.08 |
| 1991 | | 1.08 |
| 1992 | | 1.10 |
| 1993 | | 1.10 |
| 1994 | | 1.19 |
| 1995 | | 1.19 |
| 1996 | | 1.19 |
| 1997 | | 1.19 |
| 1998 | | 1.20 |
| 1999 | | 1.20 |
| 2000 | | 1.40 |
| 2001 | | 1.40 |
| 2002 | | 1.40 |
| 2003 | | 1.40 |
| 2004 | | 1.40 |
| 2005 | | 1.50 |
| 2006 | | 1.55 |
| 2007 | | 1.69 |
| 2008 | | 1.81 |
| 2009 | | 1.55 |
| 2010 | | 3.71 |
| 2011 | | |
|
|