Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 690565 | Metric tons | NA |
| 2004 | 567873 | Metric tons | -17.77% |
| 2005 | 506597 | Metric tons | -10.79% |
| 2006 | 469702 | Metric tons | -7.28% |
| 2007 | 584121 | Metric tons | 24.36% |
