Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 22762 | Metric tons | NA |
| 2010 | 24820 | Metric tons | 9.04% |
| 2011 | 24379 | Metric tons | -1.78% |
| 2012 | 22000 | Metric tons | -9.76% |
| 2013 | 22000 | Metric tons | 0.00% |
