Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 63 | Metric tons | NA |
| 2003 | 62 | Metric tons | -1.59% |
| 2004 | 56 | Metric tons | -9.68% |
| 2005 | 51.125 | Metric tons | -8.71% |
| 2006 | 51.0979995727539 | Metric tons | -0.05% |
| 2007 | 51.2999992370605 | Metric tons | 0.40% |
| 2008 | 48.0620002746582 | Metric tons | -6.31% |
| 2009 | 55.0820007324219 | Metric tons | 14.61% |
| 2010 | 74 | Metric tons | 34.35% |
| 2011 | 81 | Metric tons | 9.46% |
| 2012 | 84 | Metric tons | 3.70% |
