Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 75 | Thousand metric tons | NA |
| 2006 | 77.3000030517578 | Thousand metric tons | 3.07% |
| 2007 | 89.5 | Thousand metric tons | 15.78% |
| 2008 | 90 | Thousand metric tons | 0.56% |
| 2009 | 85 | Thousand metric tons | -5.56% |
| 2010 | 54 | Thousand metric tons | -36.47% |
| 2011 | 81.7990036010742 | Thousand metric tons | 51.48% |
| 2012 | 60.3470001220703 | Thousand metric tons | -26.23% |
| 2013 | 65 | Thousand metric tons | 7.71% |
