|
| year | production | consumption |
| 1980 | | 37.00 |
| 1981 | | 43.80 |
| 1982 | | 49.70 |
| 1983 | | 53.20 |
| 1984 | | 56.00 |
| 1985 | | 57.90 |
| 1986 | | 61.82 |
| 1987 | .50 | 66.25 |
| 1988 | .50 | 61.87 |
| 1989 | .22 | 62.29 |
| 1990 | .33 | 66.19 |
| 1991 | .30 | 62.58 |
| 1992 | .05 | 73.06 |
| 1993 | .03 | 71.85 |
| 1994 | .02 | 81.69 |
| 1995 | .03 | 85.44 |
| 1996 | .03 | 91.82 |
| 1997 | .04 | 88.47 |
| 1998 | .03 | 96.21 |
| 1999 | .04 | 95.61 |
| 2000 | .04 | 101.08 |
| 2001 | .04 | 98.84 |
| 2002 | .02 | 103.33 |
| 2003 | .02 | 106.43 |
| 2004 | .02 | 106.98 |
| 2005 | .02 | 112.43 |
| 2006 | .02 | 107.73 |
| 2007 | .02 | 103.51 |
| 2008 | .02 | 96.52 |
| 2009 | .02 | 97.64 |
| 2010 | .02 | 106.32 |
| 2011 | .02 | 115.00 |
|
|