Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 48974 | Metric tons, gross weight | NA |
| 2003 | 42632 | Metric tons, gross weight | -12.95% |
| 2004 | 50000 | Metric tons, gross weight | 17.28% |
| 2005 | 50000 | Metric tons, gross weight | 0.00% |
| 2006 | 50000 | Metric tons, gross weight | 0.00% |
