Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2007 | 86.9899978637695 | Thousand metric tons | NA |
| 2008 | 772 | Thousand metric tons | 787.46% |
| 2009 | 934 | Thousand metric tons | 20.98% |
| 2010 | 789 | Thousand metric tons | -15.52% |
| 2011 | 907 | Thousand metric tons | 14.96% |
| 2012 | 980 | Thousand metric tons | 8.05% |
