Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 217248 | Metric tons | NA |
| 2004 | 216566 | Metric tons | -0.31 % |
| 2005 | 168264 | Metric tons | -22.30 % |
| 2006 | 112787 | Metric tons | -32.97 % |
| 2007 | 110000 | Metric tons | -2.47 % |
