Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 517030 | Metric tons | NA |
| 2004 | 567504 | Metric tons | 9.76% |
| 2005 | 556129 | Metric tons | -2.00% |
| 2006 | 539239 | Metric tons | -3.04% |
| 2007 | 461901 | Metric tons | -14.34% |
| 2008 | 460000 | Metric tons | -0.41% |
| 2009 | 460000 | Metric tons | 0.00% |
