Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 493000 | Metric tons | NA |
| 2004 | 508000 | Metric tons | 3.04 % |
| 2005 | 508000 | Metric tons | 0.00 % |
| 2006 | 454000 | Metric tons | -10.63 % |
| 2007 | 409000 | Metric tons | -9.91 % |
| 2008 | 434000 | Metric tons | 6.11 % |
| 2009 | 348000 | Metric tons | -19.82 % |
