Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 668.409973144531 | Thousand metric tons | NA |
| 2004 | 730 | Thousand metric tons | 9.21% |
| 2005 | 842 | Thousand metric tons | 15.34% |
| 2006 | 1221 | Thousand metric tons | 45.01% |
| 2007 | 1260 | Thousand metric tons | 3.19% |
