Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 91937 | Metric tons, gross weight | NA |
| 2003 | 19427 | Metric tons, gross weight | -78.87% |
| 2004 | 13472 | Metric tons, gross weight | -30.65% |
| 2005 | 12367 | Metric tons, gross weight | -8.20% |
| 2006 | 13056 | Metric tons, gross weight | 5.57% |
