Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 540.051025390625 | Thousand metric tons | NA |
| 2004 | 610 | Thousand metric tons | 12.95% |
| 2005 | 672.344970703125 | Thousand metric tons | 10.22% |
| 2006 | 659.369995117188 | Thousand metric tons | -1.93% |
| 2007 | 667.052978515625 | Thousand metric tons | 1.17% |
| 2008 | 671.810974121094 | Thousand metric tons | 0.71% |
| 2009 | 45.7789993286133 | Thousand metric tons | -93.19% |
