| Year | Tons |
| 2003 | 918,643 |
| 2004 | 918,151 |
| 2005 | 1,026,395 |
| 2006 | 876,878 |
| 2007 | 879,469 |
| 2008 | 997,127 |
| 2009 | 1,165,062 |
| 2010 | 1,136,240 |
| 2011 | 958,907 |
| 2012 | 1,171,496 |