Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2004 | 1600 | Metric tons, gross weight | NA |
| 2005 | 1500 | Metric tons, gross weight | -6.25 % |
| 2006 | 1500 | Metric tons, gross weight | 0.00 % |
| 2007 | 1400 | Metric tons, gross weight | -6.67 % |
| 2008 | 1400 | Metric tons, gross weight | 0.00 % |
| 2009 | 1400 | Metric tons, gross weight | 0.00 % |
| 2010 | 1400 | Metric tons, gross weight | 0.00 % |
| 2011 | 1600 | Metric tons, gross weight | 14.29 % |
| 2012 | 1600 | Metric tons, gross weight | 0.00 % |
