Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 5000 | Metric tons | NA |
| 2003 | 4900 | Metric tons | -2.00% |
| 2004 | 4400 | Metric tons | -10.20% |
| 2005 | 3800 | Metric tons | -13.64% |
| 2006 | 4600 | Metric tons | 21.05% |
| 2007 | 5572 | Metric tons | 21.13% |
| 2008 | 5055 | Metric tons | -9.28% |
| 2009 | 12615 | Metric tons | 149.55% |
| 2010 | 12690 | Metric tons | 0.59% |
| 2011 | 12893 | Metric tons | 1.60% |
| 2012 | 13000 | Metric tons | 0.83% |
