Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 549049 | Metric tons | NA |
| 2004 | 499474 | Metric tons | -9.03% |
| 2005 | 475670 | Metric tons | -4.77% |
| 2006 | 463277 | Metric tons | -2.61% |
| 2007 | 351414 | Metric tons | -24.15% |
| 2008 | 361165 | Metric tons | 2.77% |
| 2009 | 325000 | Metric tons | -10.01% |
