Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 44000 | Metric tons | NA |
| 2010 | 24400 | Metric tons | -44.55% |
| 2011 | 25000 | Metric tons | 2.46% |
| 2012 | 24100 | Metric tons | -3.60% |
| 2013 | 25100 | Metric tons | 4.15% |
