Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 512640 | Metric tons, gross weight | NA |
| 2003 | 97238 | Metric tons, gross weight | -81.03% |
| 2004 | 138775 | Metric tons, gross weight | 42.72% |
| 2005 | 223563 | Metric tons, gross weight | 61.10% |
| 2006 | 244603 | Metric tons, gross weight | 9.41% |
| 2007 | 185760 | Metric tons, gross weight | -24.06% |
| 2008 | 268586 | Metric tons, gross weight | 44.59% |
| 2009 | 268586 | Metric tons, gross weight | 0.00% |
| 2010 | 45000 | Metric tons, gross weight | -83.25% |
| 2011 | 100000 | Metric tons, gross weight | 122.22% |
| 2012 | 100000 | Metric tons, gross weight | 0.00% |
