Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2343722 | Metric tons | NA |
| 2004 | 3251264 | Metric tons | 38.72% |
| 2005 | 3995233 | Metric tons | 22.88% |
| 2006 | 4019495 | Metric tons | 0.61% |
| 2007 | 4200000 | Metric tons | 4.49% |
| 2008 | 4727000 | Metric tons | 12.55% |
