Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 150000 | Metric tons | NA |
| 2004 | 367346 | Metric tons | 144.90% |
| 2005 | 414637 | Metric tons | 12.87% |
| 2006 | 386685 | Metric tons | -6.74% |
| 2007 | 397328 | Metric tons | 2.75% |
| 2008 | 400000 | Metric tons | 0.67% |
