Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 614 | Thousand metric tons | NA |
| 2003 | 608 | Thousand metric tons | -0.98% |
| 2004 | 808.070007324219 | Thousand metric tons | 32.91% |
| 2005 | 844.840026855469 | Thousand metric tons | 4.55% |
| 2006 | 760.815002441406 | Thousand metric tons | -9.95% |
| 2007 | 591.966979980469 | Thousand metric tons | -22.19% |
| 2008 | 725 | Thousand metric tons | 22.47% |
| 2009 | 737 | Thousand metric tons | 1.66% |
| 2010 | 723 | Thousand metric tons | -1.90% |
| 2011 | 766 | Thousand metric tons | 5.95% |
| 2012 | 760 | Thousand metric tons | -0.78% |
