| Vuosi Year |
Määrä (tonnia) Absolute amounts (tonnes) |
Suhde tuotantomäärään (% E-4) Proportional to the volume of production (per cent, E-4) |
| 1988 | 32.0 | 2.0 |
| 1991 | 25.0 | 1.6 |
| 1992 | 26.0 | 1.8 |
| 1993 | 25.0 | 1.5 |
| 1994 | 31.0 | 2.0 |
| 1995 | 28.0 | 1.6 |
| 1996 | 36.0 | 1.8 |
| 1997 | 31.0 | 1.3 |
| 1998 | 28.0 | 1.1 |
| 1999 | 31.6 | 1.3 |
| 2000 | 37.3 | 1.5 |
| 2001 | 38.3 | 1.6 |
| 2002 | 39.6 | 1.6 |
| 2003 | 43.5 | 1.7 |
| 2004 | 41.3 | 1.6 |
| 2005 | 45.4 | 1.8 |
| 2006 | 43.4 | 1.5 |
| 2007 | 38.7 | 1.3 |
| 2008 | 31.9 | 1.1 |
| 2009 | 23.4 | 0.9 |
| 2010 | 22.4 | 0.8 |
| 2011 | 24.5 | 0.9 |