Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 248 | Thousand metric tons | NA |
| 2003 | 244 | Thousand metric tons | -1.61% |
| 2004 | 231 | Thousand metric tons | -5.33% |
| 2005 | 265 | Thousand metric tons | 14.72% |
| 2006 | 123 | Thousand metric tons | -53.58% |
| 2007 | 45 | Thousand metric tons | -63.41% |
