Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 4155000 | Metric tons | NA |
| 2004 | 3862000 | Metric tons | -7.05% |
| 2005 | 3882000 | Metric tons | 0.52% |
| 2006 | 3768000 | Metric tons | -2.94% |
| 2007 | 3800000 | Metric tons | 0.85% |
