Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2097000 | Metric tons | NA |
| 2004 | 1995000 | Metric tons | -4.86% |
| 2005 | 1911000 | Metric tons | -4.21% |
| 2006 | 1800000 | Metric tons | -5.81% |
| 2007 | 1800000 | Metric tons | 0.00% |
