Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 34600 | Metric tons, gross weight | NA |
| 2003 | 63300 | Metric tons, gross weight | 82.95% |
| 2004 | 112000 | Metric tons, gross weight | 76.94% |
| 2005 | 123000 | Metric tons, gross weight | 9.82% |
| 2006 | 122000 | Metric tons, gross weight | -0.81% |
