Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 7680000 | Metric tons | NA |
| 2004 | 7760000 | Metric tons | 1.04% |
| 2005 | 7800000 | Metric tons | 0.52% |
| 2006 | 7470000 | Metric tons | -4.23% |
| 2007 | 7110000 | Metric tons | -4.82% |
