Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 11000 | Metric tons, gross weight | NA |
| 2003 | 45040 | Metric tons, gross weight | 309.45% |
| 2004 | 77386 | Metric tons, gross weight | 71.82% |
| 2005 | 140847 | Metric tons, gross weight | 82.01% |
| 2006 | 132335 | Metric tons, gross weight | -6.04% |
| 2007 | 122260 | Metric tons, gross weight | -7.61% |
| 2008 | 112613 | Metric tons, gross weight | -7.89% |
| 2009 | 133000 | Metric tons, gross weight | 18.10% |
| 2010 | 134500 | Metric tons, gross weight | 1.13% |
| 2011 | 66700 | Metric tons, gross weight | -50.41% |
| 2012 | 67000 | Metric tons, gross weight | 0.45% |
