Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 477012 | Metric tons | NA |
| 2004 | 541788 | Metric tons | 13.58% |
| 2005 | 508644 | Metric tons | -6.12% |
| 2006 | 427378 | Metric tons | -15.98% |
| 2007 | 398513 | Metric tons | -6.75% |
| 2008 | 400000 | Metric tons | 0.37% |
