Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 560 | Thousand metric tons | NA |
| 2003 | 700 | Thousand metric tons | 25.00% |
| 2004 | 161.399993896484 | Thousand metric tons | -76.94% |
| 2005 | 173.300003051758 | Thousand metric tons | 7.37% |
| 2006 | 186.300003051758 | Thousand metric tons | 7.50% |
| 2007 | 200.399993896484 | Thousand metric tons | 7.57% |
| 2008 | 200.399993896484 | Thousand metric tons | 0.00% |
