Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 2703 | Thousand metric tons | NA |
| 2010 | 2460 | Thousand metric tons | -8.99% |
| 2011 | 2884 | Thousand metric tons | 17.24% |
| 2012 | 3000 | Thousand metric tons | 4.02% |
| 2013 | 3000 | Thousand metric tons | 0.00% |
