|
| year | production | consumption |
| 1980 | | 1.10 |
| 1981 | | 1.10 |
| 1982 | | 1.10 |
| 1983 | | 1.10 |
| 1984 | | 1.20 |
| 1985 | | 1.19 |
| 1986 | | 1.11 |
| 1987 | | 1.28 |
| 1988 | | 1.32 |
| 1989 | | 1.30 |
| 1990 | | 1.33 |
| 1991 | | 1.39 |
| 1992 | | 1.38 |
| 1993 | | 1.47 |
| 1994 | | 1.63 |
| 1995 | | 1.52 |
| 1996 | | 1.51 |
| 1997 | | 1.52 |
| 1998 | | 1.60 |
| 1999 | | 1.60 |
| 2000 | | 1.79 |
| 2001 | | 1.92 |
| 2002 | | 1.97 |
| 2003 | | 1.99 |
| 2004 | | 2.01 |
| 2005 | | 2.08 |
| 2006 | | 2.22 |
| 2007 | | 2.77 |
| 2008 | | 2.87 |
| 2009 | | 3.12 |
| 2010 | | 3.39 |
| 2011 | | |
|
|