Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 431 | Thousand metric tons | NA |
| 2004 | 509 | Thousand metric tons | 18.10 % |
| 2005 | 639 | Thousand metric tons | 25.54 % |
| 2006 | 577 | Thousand metric tons | -9.70 % |
| 2007 | 641 | Thousand metric tons | 11.09 % |
| 2008 | 632 | Thousand metric tons | -1.40 % |
| 2009 | 630 | Thousand metric tons | -0.32 % |
