Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 0.791999995708466 | Thousand metric tons | NA |
| 2010 | 0.790000021457672 | Thousand metric tons | -0.25% |
| 2011 | 0.790000021457672 | Thousand metric tons | 0.00% |
| 2012 | 0.790000021457672 | Thousand metric tons | 0.00% |
| 2013 | 0.790000021457672 | Thousand metric tons | 0.00% |
