Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 20000 | Metric tons | NA |
| 2004 | 20000 | Metric tons | 0.00% |
| 2005 | 20000 | Metric tons | 0.00% |
| 2006 | 21000 | Metric tons | 5.00% |
| 2007 | 16000 | Metric tons | -23.81% |
| 2008 | 17000 | Metric tons | 6.25% |
| 2009 | 12000 | Metric tons | -29.41% |
| 2010 | 12000 | Metric tons | 0.00% |
