Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 474000 | Metric tons | NA |
| 2004 | 475000 | Metric tons | 0.21% |
| 2005 | 446000 | Metric tons | -6.11% |
| 2006 | 470000 | Metric tons | 5.38% |
| 2007 | 305905 | Metric tons | -34.91% |
| 2008 | 281119 | Metric tons | -8.10% |
| 2009 | 146318 | Metric tons | -47.95% |
| 2010 | 111000 | Metric tons | -24.14% |
| 2011 | 110000 | Metric tons | -0.90% |
| 2012 | 110000 | Metric tons | 0.00% |
| 2013 | 110000 | Metric tons | 0.00% |
