|
| year | production | consumption |
| 1980 | | .70 |
| 1981 | | .80 |
| 1982 | | .70 |
| 1983 | | .80 |
| 1984 | | |
| 1985 | | 1.04 |
| 1986 | | 1.01 |
| 1987 | | 1.05 |
| 1988 | | 1.73 |
| 1989 | | 1.91 |
| 1990 | | 2.09 |
| 1991 | | 2.33 |
| 1992 | | 2.21 |
| 1993 | | 2.46 |
| 1994 | | 2.60 |
| 1995 | | 2.53 |
| 1996 | | 2.56 |
| 1997 | | 2.59 |
| 1998 | | 2.64 |
| 1999 | | 2.64 |
| 2000 | | 2.64 |
| 2001 | | 2.80 |
| 2002 | | 2.83 |
| 2003 | | 2.94 |
| 2004 | | 2.69 |
| 2005 | | 2.63 |
| 2006 | | 2.56 |
| 2007 | | 2.35 |
| 2008 | | 1.32 |
| 2009 | | 1.46 |
| 2010 | | 1.46 |
| 2011 | | |
|
|