Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 19.7840003967285 | Thousand metric tons | NA |
| 2010 | 27.9209995269775 | Thousand metric tons | 41.13% |
| 2011 | 16.7770004272461 | Thousand metric tons | -39.91% |
| 2012 | 17 | Thousand metric tons | 1.33% |
| 2013 | 17 | Thousand metric tons | 0.00% |
