Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 74300 | Metric tons, gross weight | NA |
| 2003 | 116455 | Metric tons, gross weight | 56.74 % |
| 2004 | 320200 | Metric tons, gross weight | 174.96 % |
| 2005 | 772000 | Metric tons, gross weight | 141.10 % |
| 2006 | 966065 | Metric tons, gross weight | 25.14 % |
| 2007 | 776681 | Metric tons, gross weight | -19.60 % |
| 2008 | 750000 | Metric tons, gross weight | -3.44 % |
