Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 430 | Thousand metric tons | NA |
| 2003 | 540 | Thousand metric tons | 25.58 % |
| 2004 | 650 | Thousand metric tons | 20.37 % |
| 2005 | 1009.40002441406 | Thousand metric tons | 55.29 % |
| 2006 | 1020 | Thousand metric tons | 1.05 % |
| 2007 | 1060 | Thousand metric tons | 3.92 % |
| 2008 | 1000 | Thousand metric tons | -5.66 % |
| 2009 | 1000 | Thousand metric tons | 0.00 % |
