Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 118823 | Metric tons, gross weight | NA |
| 2003 | 110529 | Metric tons, gross weight | -6.98% |
| 2004 | 128191 | Metric tons, gross weight | 15.98% |
| 2005 | 127451 | Metric tons, gross weight | -0.58% |
| 2006 | 136374 | Metric tons, gross weight | 7.00% |
