Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 472 | Thousand metric tons | NA |
| 2004 | 602.166015625 | Thousand metric tons | 27.58% |
| 2005 | 607.252990722656 | Thousand metric tons | 0.84% |
| 2006 | 730 | Thousand metric tons | 20.21% |
| 2007 | 740 | Thousand metric tons | 1.37% |
