Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 130 | Thousand metric tons | NA |
| 2003 | 130 | Thousand metric tons | 0.00% |
| 2009 | 78 | Thousand metric tons | -40.00% |
| 2010 | 111 | Thousand metric tons | 42.31% |
| 2011 | 131 | Thousand metric tons | 18.02% |
| 2012 | 131 | Thousand metric tons | 0.00% |
| 2013 | 130 | Thousand metric tons | -0.76% |
