Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 5905 | Thousand metric tons | NA |
| 2010 | 7030 | Thousand metric tons | 19.05% |
| 2011 | 6164 | Thousand metric tons | -12.32% |
| 2012 | 7482 | Thousand metric tons | 21.38% |
| 2013 | 7495 | Thousand metric tons | 0.17% |
