Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 2040 | Thousand metric tons | NA |
| 2010 | 2440 | Thousand metric tons | 19.61% |
| 2011 | 2540 | Thousand metric tons | 4.10% |
| 2012 | 2240 | Thousand metric tons | -11.81% |
| 2013 | 2240 | Thousand metric tons | 0.00% |
