Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 64 | Thousand metric tons | NA |
| 2004 | 135.330993652344 | Thousand metric tons | 111.45% |
| 2005 | 344.990997314453 | Thousand metric tons | 154.92% |
| 2006 | 333.709991455078 | Thousand metric tons | -3.27% |
| 2007 | 287.789001464844 | Thousand metric tons | -13.76% |
| 2008 | 300 | Thousand metric tons | 4.24% |
| 2009 | 304.355987548828 | Thousand metric tons | 1.45% |
| 2010 | 292.339996337891 | Thousand metric tons | -3.95% |
| 2011 | 254.860000610352 | Thousand metric tons | -12.82% |
| 2012 | 857 | Thousand metric tons | 236.26% |
| 2013 | 857 | Thousand metric tons | 0.00% |
