Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 81456 | Metric tons | NA |
| 2004 | 101040 | Metric tons | 24.04% |
| 2005 | 116000 | Metric tons | 14.81% |
| 2006 | 90000 | Metric tons | -22.41% |
| 2007 | 90000 | Metric tons | 0.00% |
| 2008 | 90000 | Metric tons | 0.00% |
| 2009 | 75000 | Metric tons | -16.67% |
| 2010 | 85000 | Metric tons | 13.33% |
| 2011 | 85000 | Metric tons | 0.00% |
| 2012 | 85000 | Metric tons | 0.00% |
