Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 355 | Thousand metric tons | NA |
| 2003 | 384 | Thousand metric tons | 8.17 % |
| 2004 | 501 | Thousand metric tons | 30.47 % |
| 2005 | 605 | Thousand metric tons | 20.76 % |
| 2006 | 625 | Thousand metric tons | 3.31 % |
| 2007 | 722 | Thousand metric tons | 15.52 % |
| 2008 | 770 | Thousand metric tons | 6.65 % |
