Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 14980 | Metric tons | NA |
| 2004 | 18471 | Metric tons | 23.30% |
| 2005 | 18500 | Metric tons | 0.16% |
| 2006 | 19000 | Metric tons | 2.70% |
| 2007 | 21451 | Metric tons | 12.90% |
| 2008 | 31557 | Metric tons | 47.11% |
| 2009 | 119452 | Metric tons | 278.53% |
| 2010 | 44266 | Metric tons | -62.94% |
| 2011 | 27534 | Metric tons | -37.80% |
| 2012 | 22977 | Metric tons | -16.55% |
| 2013 | 47744 | Metric tons | 107.79% |
