Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2710 | Metric tons | NA |
| 2004 | 2800 | Metric tons | 3.32% |
| 2005 | 4080 | Metric tons | 45.71% |
| 2006 | 3790 | Metric tons | -7.11% |
| 2007 | 4210 | Metric tons | 11.08% |
| 2008 | 4300 | Metric tons | 2.14% |
| 2009 | 7050 | Metric tons | 63.95% |
| 2010 | 7360 | Metric tons | 4.40% |
| 2011 | 6670 | Metric tons | -9.38% |
| 2012 | 7000 | Metric tons | 4.95% |
| 2013 | 7000 | Metric tons | 0.00% |
