Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 2.64800000190735 | Metric tons | NA |
| 2006 | 2.20000004768372 | Metric tons | -16.92% |
| 2007 | 4.15000009536743 | Metric tons | 88.64% |
| 2008 | 2.29999995231628 | Metric tons | -44.58% |
| 2009 | 2.5 | Metric tons | 8.70% |
| 2010 | 4.82000017166138 | Metric tons | 92.80% |
| 2011 | 4.75 | Metric tons | -1.45% |
| 2012 | 5.22399997711182 | Metric tons | 9.98% |
