Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 480 | Metric tons | NA |
| 2004 | 493 | Metric tons | 2.71% |
| 2005 | 494 | Metric tons | 0.20% |
| 2006 | 524 | Metric tons | 6.07% |
| 2007 | 495 | Metric tons | -5.53% |
| 2008 | 530 | Metric tons | 7.07% |
| 2009 | 490 | Metric tons | -7.55% |
| 2010 | 560 | Metric tons | 14.29% |
| 2011 | 570 | Metric tons | 1.79% |
| 2012 | 560 | Metric tons | -1.75% |
| 2013 | 560 | Metric tons | 0.00% |
