Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 698 | Thousand metric tons | NA |
| 2004 | 695 | Thousand metric tons | -0.43% |
| 2005 | 701 | Thousand metric tons | 0.86% |
| 2006 | 679 | Thousand metric tons | -3.14% |
| 2007 | 680 | Thousand metric tons | 0.15% |
