|
| year | production | consumption |
| 1980 | | 1.60 |
| 1981 | | 1.50 |
| 1982 | | 1.40 |
| 1983 | | 1.40 |
| 1984 | | 1.50 |
| 1985 | | 1.53 |
| 1986 | | 1.91 |
| 1987 | | 1.58 |
| 1988 | | 1.13 |
| 1989 | | 1.58 |
| 1990 | | 2.22 |
| 1991 | | 2.47 |
| 1992 | | 2.12 |
| 1993 | | 2.11 |
| 1994 | | 2.00 |
| 1995 | | 2.29 |
| 1996 | | 1.94 |
| 1997 | | 3.19 |
| 1998 | | 3.21 |
| 1999 | | 3.26 |
| 2000 | | 4.71 |
| 2001 | | 6.26 |
| 2002 | | 6.01 |
| 2003 | | 6.29 |
| 2004 | | 6.75 |
| 2005 | | 7.12 |
| 2006 | 2.26 | 7.20 |
| 2007 | 3.00 | 7.33 |
| 2008 | 3.51 | 3.55 |
| 2009 | 3.99 | 3.50 |
| 2010 | 4.25 | 3.49 |
| 2011 | | |
|
|