Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 1600 | Thousand metric tons | NA |
| 2010 | 1800 | Thousand metric tons | 12.50% |
| 2011 | 1800 | Thousand metric tons | 0.00% |
| 2012 | 1850 | Thousand metric tons | 2.78% |
| 2013 | 1850 | Thousand metric tons | 0.00% |
