Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 271.81201171875 | Thousand metric tons | NA |
| 2003 | 366.736999511719 | Thousand metric tons | 34.92% |
| 2004 | 283 | Thousand metric tons | -22.83% |
| 2005 | 377 | Thousand metric tons | 33.22% |
| 2006 | 104 | Thousand metric tons | -72.41% |
| 2007 | 100 | Thousand metric tons | -3.85% |
| 2008 | 3 | Thousand metric tons | -97.00% |
