Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 132 | Thousand metric tons | NA |
| 2004 | 130 | Thousand metric tons | -1.52% |
| 2005 | 135 | Thousand metric tons | 3.85% |
| 2006 | 161 | Thousand metric tons | 19.26% |
| 2007 | 160 | Thousand metric tons | -0.62% |
