Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 365000 | Metric tons | NA |
| 2004 | 360000 | Metric tons | -1.37% |
| 2005 | 360000 | Metric tons | 0.00% |
| 2006 | 370000 | Metric tons | 2.78% |
| 2007 | 375000 | Metric tons | 1.35% |
| 2008 | 380000 | Metric tons | 1.33% |
| 2009 | 385000 | Metric tons | 1.32% |
