Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 130329 | Metric tons | NA |
| 2004 | 87609 | Metric tons | -32.78% |
| 2005 | 110833 | Metric tons | 26.51% |
| 2006 | 125000 | Metric tons | 12.78% |
| 2007 | 125000 | Metric tons | 0.00% |
| 2008 | 96902 | Metric tons | -22.48% |
| 2009 | 36127 | Metric tons | -62.72% |
| 2010 | 31429 | Metric tons | -13.00% |
| 2011 | 40669 | Metric tons | 29.40% |
| 2012 | 46192 | Metric tons | 13.58% |
| 2013 | 40000 | Metric tons | -13.40% |
