Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 19000 | Metric tons | NA |
| 2004 | 18000 | Metric tons | -5.26% |
| 2005 | 19000 | Metric tons | 5.56% |
| 2006 | 20000 | Metric tons | 5.26% |
| 2007 | 21000 | Metric tons | 5.00% |
| 2008 | 20000 | Metric tons | -4.76% |
| 2009 | 261 | Metric tons | -98.70% |
| 2010 | 254 | Metric tons | -2.68% |
| 2011 | 250 | Metric tons | -1.57% |
| 2012 | 245 | Metric tons | -2.00% |
| 2013 | 240 | Metric tons | -2.04% |
