Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1463 | Thousand metric tons | NA |
| 2003 | 1658 | Thousand metric tons | 13.33 % |
| 2004 | 1789.10205078125 | Thousand metric tons | 7.91 % |
| 2005 | 2123.25610351563 | Thousand metric tons | 18.68 % |
| 2006 | 2174.09008789063 | Thousand metric tons | 2.39 % |
| 2007 | 2545.66088867188 | Thousand metric tons | 17.09 % |
| 2008 | 3134.57104492188 | Thousand metric tons | 23.13 % |
