Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 6000 | Metric tons | NA |
| 2004 | 5510 | Metric tons | -8.17% |
| 2005 | 4410 | Metric tons | -19.96% |
| 2006 | 4352 | Metric tons | -1.32% |
| 2007 | 4515 | Metric tons | 3.75% |
| 2008 | 4593 | Metric tons | 1.73% |
| 2009 | 4606 | Metric tons | 0.28% |
| 2010 | 4756 | Metric tons | 3.26% |
| 2011 | 6272 | Metric tons | 31.88% |
| 2012 | 9221 | Metric tons | 47.02% |
| 2013 | 14249 | Metric tons | 54.53% |
