Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 554 | Thousand metric tons | NA |
| 2010 | 500 | Thousand metric tons | -9.75% |
| 2011 | 501 | Thousand metric tons | 0.20% |
| 2012 | 528 | Thousand metric tons | 5.39% |
| 2013 | 530 | Thousand metric tons | 0.38% |
