Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 450 | Metric tons | NA |
| 2003 | 465 | Metric tons | 3.33% |
| 2004 | 407 | Metric tons | -12.47% |
| 2005 | 418.505004882813 | Metric tons | 2.83% |
| 2006 | 472.2080078125 | Metric tons | 12.83% |
| 2007 | 524.989013671875 | Metric tons | 11.18% |
| 2008 | 1113.76403808594 | Metric tons | 112.15% |
| 2009 | 1325.72900390625 | Metric tons | 19.03% |
| 2010 | 1259.38793945313 | Metric tons | -5.00% |
| 2011 | 1213.58605957031 | Metric tons | -3.64% |
| 2012 | 1214.02099609375 | Metric tons | 0.04% |
