Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 20 | Metric tons | NA |
| 2003 | 22 | Metric tons | 10.00% |
| 2004 | 24 | Metric tons | 9.09% |
| 2005 | 23.7859992980957 | Metric tons | -0.89% |
| 2006 | 20.076000213623 | Metric tons | -15.60% |
| 2007 | 24.1669998168945 | Metric tons | 20.38% |
| 2008 | 28.7999992370605 | Metric tons | 19.17% |
| 2009 | 22.4500007629395 | Metric tons | -22.05% |
| 2010 | 23.7099990844727 | Metric tons | 5.61% |
| 2011 | 28.3799991607666 | Metric tons | 19.70% |
| 2012 | 28.3999996185303 | Metric tons | 0.07% |
