Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 6872 | Metric tons | NA |
| 2004 | 6866 | Metric tons | -0.09% |
| 2005 | 8939 | Metric tons | 30.19% |
| 2006 | 8900 | Metric tons | -0.44% |
| 2007 | 8950 | Metric tons | 0.56% |
| 2008 | 8000 | Metric tons | -10.61% |
| 2009 | 8655 | Metric tons | 8.19% |
| 2010 | 13731 | Metric tons | 58.65% |
| 2011 | 8154 | Metric tons | -40.62% |
| 2012 | 8000 | Metric tons | -1.89% |
