Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2008 | 10.5880002975464 | Thousand metric tons | NA |
| 2009 | 12.9209995269775 | Thousand metric tons | 22.03% |
| 2010 | 21.2000007629395 | Thousand metric tons | 64.07% |
| 2011 | 17.6000003814697 | Thousand metric tons | -16.98% |
| 2012 | 26 | Thousand metric tons | 47.73% |
| 2013 | 2.40000009536743 | Thousand metric tons | -90.77% |
