Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 2816.23510742188 | Thousand metric tons | NA |
| 2010 | 3291.06298828125 | Thousand metric tons | 16.86% |
| 2011 | 2714.73510742188 | Thousand metric tons | -17.51% |
| 2012 | 3000 | Thousand metric tons | 10.51% |
| 2013 | 3000 | Thousand metric tons | 0.00% |
