Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5000 | Metric tons, gross weight | NA |
| 2004 | 5000 | Metric tons, gross weight | 0.00% |
| 2005 | 5000 | Metric tons, gross weight | 0.00% |
| 2006 | 5000 | Metric tons, gross weight | 0.00% |
| 2007 | 5000 | Metric tons, gross weight | 0.00% |
| 2008 | 5000 | Metric tons, gross weight | 0.00% |
| 2009 | 5000 | Metric tons, gross weight | 0.00% |
| 2010 | 5200 | Metric tons, gross weight | 4.00% |
| 2011 | 5200 | Metric tons, gross weight | 0.00% |
| 2012 | 5400 | Metric tons, gross weight | 3.85% |
