|
| year | production | consumption |
| 1980 | | |
| 1981 | | |
| 1982 | | |
| 1983 | | |
| 1984 | | |
| 1985 | | 2.48 |
| 1986 | | 3.74 |
| 1987 | | 4.07 |
| 1988 | | 3.96 |
| 1989 | | 4.12 |
| 1990 | | 4.00 |
| 1991 | | 5.17 |
| 1992 | | 5.78 |
| 1993 | | 5.99 |
| 1994 | | 6.83 |
| 1995 | | 7.26 |
| 1996 | | 9.05 |
| 1997 | | 11.09 |
| 1998 | | 14.33 |
| 1999 | | 15.40 |
| 2000 | | 14.90 |
| 2001 | | 15.26 |
| 2002 | | 15.51 |
| 2003 | | 15.67 |
| 2004 | | 16.15 |
| 2005 | | 16.72 |
| 2006 | | 16.92 |
| 2007 | | 16.70 |
| 2008 | | 17.25 |
| 2009 | | 19.99 |
| 2010 | | 21.94 |
| 2011 | | 19.00 |
|
|