Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 26055 | Metric tons | NA |
| 2004 | 25103 | Metric tons | -3.65% |
| 2005 | 24191 | Metric tons | -3.63% |
| 2006 | 19279 | Metric tons | -20.31% |
| 2007 | 18952 | Metric tons | -1.70% |
| 2008 | 20089 | Metric tons | 6.00% |
| 2009 | 50438 | Metric tons | 151.07% |
| 2010 | 49976 | Metric tons | -0.92% |
| 2011 | 55000 | Metric tons | 10.05% |
| 2012 | 50000 | Metric tons | -9.09% |
| 2013 | 55000 | Metric tons | 10.00% |
