Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 186 | Thousand metric tons | NA |
| 2006 | 218.121002197266 | Thousand metric tons | 17.27% |
| 2007 | 237.190002441406 | Thousand metric tons | 8.74% |
| 2008 | 215.787002563477 | Thousand metric tons | -9.02% |
| 2009 | 280.938995361328 | Thousand metric tons | 30.19% |
| 2010 | 339.428985595703 | Thousand metric tons | 20.82% |
| 2011 | 488.576995849609 | Thousand metric tons | 43.94% |
| 2012 | 397.802001953125 | Thousand metric tons | -18.58% |
| 2013 | 400 | Thousand metric tons | 0.55% |
