Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3200 | Metric tons | NA |
| 2004 | 15000 | Metric tons | 368.75% |
| 2005 | 17700 | Metric tons | 18.00% |
| 2006 | 19100 | Metric tons | 7.91% |
| 2007 | 18800 | Metric tons | -1.57% |
| 2008 | 18700 | Metric tons | -0.53% |
| 2009 | 18500 | Metric tons | -1.07% |
| 2010 | 18000 | Metric tons | -2.70% |
| 2011 | 19000 | Metric tons | 5.56% |
| 2012 | 19000 | Metric tons | 0.00% |
