Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 26 | Thousand metric tons | NA |
| 2004 | 30 | Thousand metric tons | 15.38% |
| 2005 | 16.4179992675781 | Thousand metric tons | -45.27% |
| 2006 | 19.1040000915527 | Thousand metric tons | 16.36% |
| 2007 | 25.4050006866455 | Thousand metric tons | 32.98% |
| 2008 | 25.4969997406006 | Thousand metric tons | 0.36% |
| 2009 | 23.0270004272461 | Thousand metric tons | -9.69% |
| 2010 | 30.9249992370605 | Thousand metric tons | 34.30% |
| 2011 | 22.9379997253418 | Thousand metric tons | -25.83% |
| 2012 | 25 | Thousand metric tons | 8.99% |
