|
| year | production | consumption |
| 1980 | | .02 |
| 1981 | | .17 |
| 1982 | | .21 |
| 1983 | | .19 |
| 1984 | | .18 |
| 1985 | | .23 |
| 1986 | | .23 |
| 1987 | | .27 |
| 1988 | | .27 |
| 1989 | | .27 |
| 1990 | | .63 |
| 1991 | | .63 |
| 1992 | | .64 |
| 1993 | | .65 |
| 1994 | | .74 |
| 1995 | | .86 |
| 1996 | | .93 |
| 1997 | | .91 |
| 1998 | | .96 |
| 1999 | | .96 |
| 2000 | | .98 |
| 2001 | | 1.05 |
| 2002 | | 1.09 |
| 2003 | | 1.13 |
| 2004 | | 1.14 |
| 2005 | | 1.15 |
| 2006 | | 1.17 |
| 2007 | | 1.55 |
| 2008 | | 1.59 |
| 2009 | | 2.00 |
| 2010 | | 2.00 |
| 2011 | | |
|
|