Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 16670 | Metric tons | NA |
| 2004 | 13986 | Metric tons | -16.10% |
| 2005 | 17001 | Metric tons | 21.56% |
| 2006 | 18000 | Metric tons | 5.88% |
| 2007 | 19000 | Metric tons | 5.56% |
