Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 346315 | Metric tons | NA |
| 2004 | 364315 | Metric tons | 5.20% |
| 2005 | 349109 | Metric tons | -4.17% |
| 2006 | 459209 | Metric tons | 31.54% |
| 2007 | 438696 | Metric tons | -4.47% |
| 2008 | 432840 | Metric tons | -1.33% |
