Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 19219 | Metric tons | NA |
| 2004 | 39072 | Metric tons | 103.30% |
| 2005 | 54903 | Metric tons | 40.52% |
| 2006 | 49619 | Metric tons | -9.62% |
| 2007 | 50000 | Metric tons | 0.77% |
