Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 14585 | Metric tons | NA |
| 2004 | 20419 | Metric tons | 40.00% |
| 2005 | 33682 | Metric tons | 64.95% |
| 2006 | 49225 | Metric tons | 46.15% |
| 2007 | 68377 | Metric tons | 38.91% |
