Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 50000 | Metric tons | NA |
| 2004 | 50000 | Metric tons | 0.00% |
| 2005 | 30000 | Metric tons | -40.00% |
| 2006 | 30000 | Metric tons | 0.00% |
| 2007 | 29800 | Metric tons | -0.67% |
| 2008 | 32000 | Metric tons | 7.38% |
| 2009 | 32000 | Metric tons | 0.00% |
| 2010 | 33132 | Metric tons | 3.54% |
| 2011 | 30000 | Metric tons | -9.45% |
| 2012 | 30000 | Metric tons | 0.00% |
| 2013 | 30000 | Metric tons | 0.00% |
