Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 13568 | Metric tons | NA |
| 2004 | 16000 | Metric tons | 17.92% |
| 2005 | 17391 | Metric tons | 8.69% |
| 2006 | 16410 | Metric tons | -5.64% |
| 2007 | 19578 | Metric tons | 19.31% |
| 2008 | 19500 | Metric tons | -0.40% |
| 2009 | 19500 | Metric tons | 0.00% |
