Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3009245 | Metric tons | NA |
| 2004 | 2773220 | Metric tons | -7.84% |
| 2005 | 2767091 | Metric tons | -0.22% |
| 2006 | 2399458 | Metric tons | -13.29% |
| 2007 | 2630356 | Metric tons | 9.62% |
