Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 27444 | Metric tons, gross weight | NA |
| 2003 | 13000 | Metric tons, gross weight | -52.63 % |
| 2004 | 26600 | Metric tons, gross weight | 104.62 % |
| 2005 | 50400 | Metric tons, gross weight | 89.47 % |
| 2006 | 70500 | Metric tons, gross weight | 39.88 % |
| 2007 | 407822 | Metric tons, gross weight | 478.47 % |
| 2008 | 784082 | Metric tons, gross weight | 92.26 % |
