Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 923 | Thousand metric tons | NA |
| 2004 | 815 | Thousand metric tons | -11.70% |
| 2005 | 711 | Thousand metric tons | -12.76% |
| 2006 | 674 | Thousand metric tons | -5.20% |
| 2007 | 670 | Thousand metric tons | -0.59% |
