Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 84720 | Metric tons, gross weight | NA |
| 2003 | 141899 | Metric tons, gross weight | 67.49% |
| 2004 | 194945 | Metric tons, gross weight | 37.38% |
| 2005 | 200000 | Metric tons, gross weight | 2.59% |
| 2006 | 200000 | Metric tons, gross weight | 0.00% |