Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 11786 | Metric tons | NA |
| 2003 | 11800 | Metric tons | 0.12% |
| 2004 | 7825 | Metric tons | -33.69% |
| 2005 | 10000 | Metric tons | 27.80% |
| 2006 | 4496 | Metric tons | -55.04% |
| 2007 | 4500 | Metric tons | 0.09% |
| 2008 | 4500 | Metric tons | 0.00% |
| 2009 | 4000 | Metric tons | -11.11% |
| 2010 | 4034 | Metric tons | 0.85% |
| 2011 | 3775 | Metric tons | -6.42% |
| 2012 | 3800 | Metric tons | 0.66% |
| 2013 | 3850 | Metric tons | 1.32% |
