Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 798407 | Metric tons | NA |
| 2004 | 654711 | Metric tons | -18.00% |
| 2005 | 877147 | Metric tons | 33.97% |
| 2006 | 961800 | Metric tons | 9.65% |
| 2007 | 962000 | Metric tons | 0.02% |
