Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 4222 | Metric tons | NA |
| 2003 | 3715 | Metric tons | -12.01% |
| 2004 | 4240 | Metric tons | 14.13% |
| 2005 | 3462 | Metric tons | -18.35% |
| 2006 | 3285 | Metric tons | -5.11% |
| 2007 | 3276 | Metric tons | -0.27% |
| 2008 | 2852 | Metric tons | -12.94% |
| 2009 | 3079 | Metric tons | 7.96% |
| 2010 | 6392 | Metric tons | 107.60% |
| 2011 | 6748 | Metric tons | 5.57% |
| 2012 | 5840 | Metric tons | -13.46% |
