Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 102 | Thousand metric tons | NA |
| 2004 | 201.093994140625 | Thousand metric tons | 97.15% |
| 2005 | 774 | Thousand metric tons | 284.89% |
| 2006 | 775 | Thousand metric tons | 0.13% |
| 2007 | 775 | Thousand metric tons | 0.00% |
| 2008 | 775 | Thousand metric tons | 0.00% |
| 2009 | 761.330993652344 | Thousand metric tons | -1.76% |
| 2010 | 553.39599609375 | Thousand metric tons | -27.31% |
| 2011 | 686.150024414063 | Thousand metric tons | 23.99% |
| 2012 | 578.543029785156 | Thousand metric tons | -15.68% |
| 2013 | 600 | Thousand metric tons | 3.71% |
