Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 597 | Thousand metric tons | NA |
| 2003 | 700 | Thousand metric tons | 17.25 % |
| 2004 | 754 | Thousand metric tons | 7.71 % |
| 2005 | 1315 | Thousand metric tons | 74.40 % |
| 2006 | 1373 | Thousand metric tons | 4.41 % |
| 2007 | 1400 | Thousand metric tons | 1.97 % |
| 2008 | 1400 | Thousand metric tons | 0.00 % |
