Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 34 | Thousand metric tons | NA |
| 2004 | 34.4000015258789 | Thousand metric tons | 1.18% |
| 2005 | 31 | Thousand metric tons | -9.88% |
| 2006 | 34.4000015258789 | Thousand metric tons | 10.97% |
