Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1377.29699707031 | Thousand metric tons | NA |
| 2004 | 1579 | Thousand metric tons | 14.64% |
| 2005 | 1536 | Thousand metric tons | -2.72% |
| 2006 | 1627 | Thousand metric tons | 5.92% |
| 2007 | 1666 | Thousand metric tons | 2.40% |
