Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 194900 | Metric tons | NA |
| 2004 | 200000 | Metric tons | 2.62% |
| 2005 | 127000 | Metric tons | -36.50% |
| 2006 | 140000 | Metric tons | 10.24% |
| 2007 | 140000 | Metric tons | 0.00% |
