Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 800000 | Metric tons | NA |
| 2004 | 770000 | Metric tons | -3.75% |
| 2005 | 750000 | Metric tons | -2.60% |
| 2006 | 760000 | Metric tons | 1.33% |
| 2007 | 730000 | Metric tons | -3.95% |
| 2008 | 650000 | Metric tons | -10.96% |
