Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 86365 | Metric tons | NA |
| 2004 | 81901 | Metric tons | -5.17% |
| 2005 | 59356 | Metric tons | -27.53% |
| 2006 | 51602 | Metric tons | -13.06% |
| 2007 | 51602 | Metric tons | 0.00% |
