Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 10.5 | Thousand metric tons | NA |
| 2010 | 10.3999996185303 | Thousand metric tons | -0.95% |
| 2011 | 11 | Thousand metric tons | 5.77% |
| 2012 | 12 | Thousand metric tons | 9.09% |
| 2013 | 13 | Thousand metric tons | 8.33% |
