Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 12046 | Metric tons | NA |
| 2003 | 9755 | Metric tons | -19.02% |
| 2004 | 12100 | Metric tons | 24.04% |
| 2005 | 8924 | Metric tons | -26.25% |
| 2006 | 8585 | Metric tons | -3.80% |
| 2007 | 7991 | Metric tons | -6.92% |
| 2008 | 8000 | Metric tons | 0.11% |
| 2009 | 15929 | Metric tons | 99.11% |
| 2010 | 15733 | Metric tons | -1.23% |
| 2011 | 7820 | Metric tons | -50.30% |
| 2012 | 7084 | Metric tons | -9.41% |
| 2013 | 8000 | Metric tons | 12.93% |
