Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3930.09912109375 | Thousand metric tons | NA |
| 2004 | 4575 | Thousand metric tons | 16.41% |
| 2005 | 4907 | Thousand metric tons | 7.26% |
| 2006 | 4900 | Thousand metric tons | -0.14% |
| 2007 | 4864 | Thousand metric tons | -0.73% |
