|
| year | production | consumption |
| 1980 | 2.93 | 1.34 |
| 1981 | 3.02 | 1.39 |
| 1982 | 3.02 | 1.35 |
| 1983 | 3.44 | 1.47 |
| 1984 | 3.67 | 1.53 |
| 1985 | 3.77 | 1.55 |
| 1986 | 3.91 | 1.54 |
| 1987 | 4.34 | 1.57 |
| 1988 | 4.68 | 1.60 |
| 1989 | 5.59 | 1.67 |
| 1990 | 5.80 | 1.71 |
| 1991 | 6.18 | 1.62 |
| 1992 | 6.86 | 1.71 |
| 1993 | 7.12 | 1.71 |
| 1994 | 7.77 | 1.68 |
| 1995 | 8.35 | 1.79 |
| 1996 | 9.26 | 1.69 |
| 1997 | 9.58 | 1.75 |
| 1998 | 9.33 | 1.81 |
| 1999 | 9.53 | 1.88 |
| 2000 | 10.30 | 1.99 |
| 2001 | 10.30 | 1.89 |
| 2002 | 10.69 | 1.94 |
| 2003 | 10.64 | 1.82 |
| 2004 | 10.79 | 1.93 |
| 2005 | 10.66 | 2.00 |
| 2006 | 10.12 | 1.84 |
| 2007 | 9.92 | 1.98 |
| 2008 | 10.13 | 1.94 |
| 2009 | 9.88 | 1.90 |
| 2010 | 9.45 | 1.87 |
|
|