Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 404000 | Metric tons | NA |
| 2004 | 368000 | Metric tons | -8.91% |
| 2005 | 376000 | Metric tons | 2.17% |
| 2006 | 398000 | Metric tons | 5.85% |
| 2007 | 400000 | Metric tons | 0.50% |
| 2008 | 400000 | Metric tons | 0.00% |
| 2009 | 392000 | Metric tons | -2.00% |
