Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2675 | Thousand metric tons | NA |
| 2004 | 2684 | Thousand metric tons | 0.34% |
| 2005 | 2194 | Thousand metric tons | -18.26% |
| 2006 | 2802 | Thousand metric tons | 27.71% |
| 2007 | 2800 | Thousand metric tons | -0.07% |
