|
| year | production | consumption |
| 1980 | | 2.87 |
| 1981 | | 3.02 |
| 1982 | | 3.22 |
| 1983 | | 3.37 |
| 1984 | | 3.47 |
| 1985 | | 3.55 |
| 1986 | | 3.33 |
| 1987 | | 3.54 |
| 1988 | | 3.70 |
| 1989 | | 4.04 |
| 1990 | | 4.35 |
| 1991 | | 3.98 |
| 1992 | | 3.98 |
| 1993 | | 3.99 |
| 1994 | | 4.04 |
| 1995 | | 4.24 |
| 1996 | | 4.35 |
| 1997 | | 4.37 |
| 1998 | | 4.39 |
| 1999 | | 4.39 |
| 2000 | | 4.46 |
| 2001 | | 4.46 |
| 2002 | | 4.49 |
| 2003 | | 4.53 |
| 2004 | | 4.58 |
| 2005 | | 4.64 |
| 2006 | | 4.92 |
| 2007 | | 4.78 |
| 2008 | | 4.86 |
| 2009 | | 4.88 |
| 2010 | | 4.66 |
| 2011 | | |
|
|