Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1137000 | Metric tons | NA |
| 2004 | 1291000 | Metric tons | 13.54% |
| 2005 | 1380000 | Metric tons | 6.89% |
| 2006 | 1658000 | Metric tons | 20.14% |
| 2007 | 1631000 | Metric tons | -1.63% |
