Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 56.9000015258789 | Thousand metric tons | NA |
| 2004 | 59 | Thousand metric tons | 3.69% |
| 2005 | 48 | Thousand metric tons | -18.64% |
| 2006 | 72 | Thousand metric tons | 50.00% |
| 2007 | 73 | Thousand metric tons | 1.39% |
