Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 162 | Thousand metric tons | NA |
| 2004 | 170 | Thousand metric tons | 4.94% |
| 2005 | 113 | Thousand metric tons | -33.53% |
| 2006 | 150 | Thousand metric tons | 32.74% |
| 2007 | 160 | Thousand metric tons | 6.67% |
