|
| year | production | consumption |
| 1980 | 1.05 | 1.67 |
| 1981 | 1.15 | 1.74 |
| 1982 | 1.18 | 1.78 |
| 1983 | 1.23 | 1.82 |
| 1984 | 1.35 | 2.13 |
| 1985 | 1.42 | 2.20 |
| 1986 | 1.46 | 2.21 |
| 1987 | 1.44 | 2.22 |
| 1988 | 1.46 | 2.23 |
| 1989 | 1.44 | 2.23 |
| 1990 | 1.39 | 2.13 |
| 1991 | 1.29 | 1.90 |
| 1992 | | |
| 1993 | | |
| 1994 | | |
| 1995 | | |
| 1996 | | |
| 1997 | | |
| 1998 | | |
| 1999 | | |
| 2000 | | |
| 2001 | | |
| 2002 | | |
| 2003 | | |
| 2004 | | |
| 2005 | | |
| 2006 | | |
| 2007 | | |
| 2008 | | |
| 2009 | | |
| 2010 | | |
|
|