Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 500 | Thousand metric tons | NA |
| 2004 | 500 | Thousand metric tons | 0.00% |
| 2005 | 500 | Thousand metric tons | 0.00% |
| 2006 | 500 | Thousand metric tons | 0.00% |
| 2007 | 500 | Thousand metric tons | 0.00% |
| 2008 | 500 | Thousand metric tons | 0.00% |
| 2009 | 209.830993652344 | Thousand metric tons | -58.03% |
| 2010 | 260.195007324219 | Thousand metric tons | 24.00% |
| 2011 | 250 | Thousand metric tons | -3.92% |
| 2012 | 230 | Thousand metric tons | -8.00% |
| 2013 | 200 | Thousand metric tons | -13.04% |
