Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 9107 | Thousand metric tons | NA |
| 2004 | 10578 | Thousand metric tons | 16.15% |
| 2005 | 8336 | Thousand metric tons | -21.19% |
| 2006 | 9991.6376953125 | Thousand metric tons | 19.86% |
| 2007 | 10630.7158203125 | Thousand metric tons | 6.40% |
