Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 205 | Thousand metric tons | NA |
| 2003 | 272 | Thousand metric tons | 32.68 % |
| 2004 | 307.100006103516 | Thousand metric tons | 12.90 % |
| 2005 | 331.200012207031 | Thousand metric tons | 7.85 % |
| 2006 | 202.199996948242 | Thousand metric tons | -38.95 % |
| 2007 | 326.200012207031 | Thousand metric tons | 61.33 % |
| 2008 | 330 | Thousand metric tons | 1.16 % |
