Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 421 | Thousand metric tons | NA |
| 2003 | 394 | Thousand metric tons | -6.41 % |
| 2004 | 490.372009277344 | Thousand metric tons | 24.46 % |
| 2005 | 501.585998535156 | Thousand metric tons | 2.29 % |
| 2006 | 615.072021484375 | Thousand metric tons | 22.63 % |
| 2007 | 706.703979492188 | Thousand metric tons | 14.90 % |
| 2008 | 705 | Thousand metric tons | -0.24 % |
