Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 3911 | Thousand metric tons | NA |
| 2003 | 5217 | Thousand metric tons | 33.39 % |
| 2004 | 6254.06494140625 | Thousand metric tons | 19.88 % |
| 2005 | 7594.5068359375 | Thousand metric tons | 21.43 % |
| 2006 | 8929.3759765625 | Thousand metric tons | 17.58 % |
| 2007 | 9602.25 | Thousand metric tons | 7.54 % |
| 2008 | 9703.2998046875 | Thousand metric tons | 1.05 % |
