|
| year | production | consumption |
| 1980 | .33 | .50 |
| 1981 | .35 | .49 |
| 1982 | .38 | .50 |
| 1983 | .41 | .53 |
| 1984 | .44 | .56 |
| 1985 | .46 | .58 |
| 1986 | .54 | .62 |
| 1987 | .52 | .63 |
| 1988 | .56 | .67 |
| 1989 | .58 | .67 |
| 1990 | .59 | .71 |
| 1991 | .61 | .71 |
| 1992 | .60 | .70 |
| 1993 | .61 | .72 |
| 1994 | .63 | .77 |
| 1995 | .63 | .78 |
| 1996 | .66 | .77 |
| 1997 | .69 | .79 |
| 1998 | .65 | .77 |
| 1999 | .67 | .81 |
| 2000 | .68 | .83 |
| 2001 | .68 | .84 |
| 2002 | .71 | .85 |
| 2003 | .65 | .85 |
| 2004 | .65 | .88 |
| 2005 | .61 | .84 |
| 2006 | .63 | .86 |
| 2007 | .67 | .86 |
| 2008 | .69 | .85 |
| 2009 | .70 | .84 |
| 2010 | .75 | .86 |
|
|