Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1434 | Thousand metric tons | NA |
| 2004 | 1563 | Thousand metric tons | 9.00% |
| 2005 | 1632 | Thousand metric tons | 4.41% |
| 2006 | 1672 | Thousand metric tons | 2.45% |
| 2007 | 1700 | Thousand metric tons | 1.67% |
