Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 27500 | Metric tons | NA |
| 2003 | 30300 | Metric tons | 10.18 % |
| 2004 | 31800 | Metric tons | 4.95 % |
| 2005 | 44200 | Metric tons | 38.99 % |
| 2006 | 83000 | Metric tons | 87.78 % |
| 2007 | 108000 | Metric tons | 30.12 % |
| 2008 | 189000 | Metric tons | 75.00 % |
