Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 11114 | Thousand metric tons | NA |
| 2004 | 11698 | Thousand metric tons | 5.25% |
| 2005 | 8906 | Thousand metric tons | -23.87% |
| 2006 | 11238 | Thousand metric tons | 26.18% |
| 2007 | 11000 | Thousand metric tons | -2.12% |
