Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 36 | Thousand metric tons | NA |
| 2004 | 27 | Thousand metric tons | -25.00% |
| 2005 | 34.0449981689453 | Thousand metric tons | 26.09% |
| 2006 | 38.5429992675781 | Thousand metric tons | 13.21% |
| 2007 | 49.6040000915527 | Thousand metric tons | 28.70% |
| 2008 | 36.9959983825684 | Thousand metric tons | -25.42% |
| 2009 | 62.2700004577637 | Thousand metric tons | 68.32% |
| 2010 | 54.4669990539551 | Thousand metric tons | -12.53% |
| 2011 | 60.6510009765625 | Thousand metric tons | 11.35% |
| 2012 | 55 | Thousand metric tons | -9.32% |
