Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 25000 | Metric tons | NA |
| 2004 | 28000 | Metric tons | 12.00% |
| 2005 | 28000 | Metric tons | 0.00% |
| 2006 | 28000 | Metric tons | 0.00% |
| 2007 | 28000 | Metric tons | 0.00% |
| 2008 | 27000 | Metric tons | -3.57% |
| 2009 | 15000 | Metric tons | -44.44% |
| 2010 | 20000 | Metric tons | 33.33% |
| 2011 | 25000 | Metric tons | 25.00% |
| 2012 | 24000 | Metric tons | -4.00% |
| 2013 | 20000 | Metric tons | -16.67% |
