Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 2.64800000190735 | Metric tons | NA |
| 2006 | 2.20000004768372 | Metric tons | -16.92 % |
| 2007 | 4.15000009536743 | Metric tons | 88.64 % |
| 2008 | 4 | Metric tons | -3.61 % |
| 2009 | 4 | Metric tons | 0.00 % |
