Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 90854 | Metric tons | NA |
| 2004 | 125684 | Metric tons | 38.34% |
| 2005 | 151307 | Metric tons | 20.39% |
| 2006 | 170728 | Metric tons | 12.84% |
| 2007 | 170728 | Metric tons | 0.00% |
| 2008 | 291562 | Metric tons | 70.78% |
