Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1210 | Metric tons | NA |
| 2003 | 1313 | Metric tons | 8.51% |
| 2004 | 1360 | Metric tons | 3.58% |
| 2005 | 1399.53894042969 | Metric tons | 2.91% |
| 2006 | 1607.16394042969 | Metric tons | 14.84% |
| 2007 | 1936.46704101563 | Metric tons | 20.49% |
| 2008 | 1405.02001953125 | Metric tons | -27.44% |
| 2009 | 1301.01794433594 | Metric tons | -7.40% |
| 2010 | 1286.68798828125 | Metric tons | -1.10% |
| 2011 | 1291.27197265625 | Metric tons | 0.36% |
| 2012 | 1194.52099609375 | Metric tons | -7.49% |
