Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3600000 | Metric tons | NA |
| 2004 | 3260000 | Metric tons | -9.44% |
| 2005 | 2730000 | Metric tons | -16.26% |
| 2006 | 2540000 | Metric tons | -6.96% |
| 2007 | 2660000 | Metric tons | 4.72% |
