Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 466 | Thousand metric tons | NA |
| 2003 | 506 | Thousand metric tons | 8.58% |
| 2004 | 615 | Thousand metric tons | 21.54% |
| 2005 | 726 | Thousand metric tons | 18.05% |
| 2006 | 848.900024414063 | Thousand metric tons | 16.93% |
| 2007 | 937.400024414063 | Thousand metric tons | 10.43% |
| 2008 | 808 | Thousand metric tons | -13.80% |
| 2009 | 326 | Thousand metric tons | -59.65% |
| 2010 | 375 | Thousand metric tons | 15.03% |
| 2011 | 449 | Thousand metric tons | 19.73% |
| 2012 | 450 | Thousand metric tons | 0.22% |
