Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 484507 | Metric tons | NA |
| 2004 | 531109 | Metric tons | 9.62% |
| 2005 | 311501 | Metric tons | -41.35% |
| 2006 | 310000 | Metric tons | -0.48% |
| 2007 | 350000 | Metric tons | 12.90% |
