Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 460000 | Metric tons | NA |
| 2010 | 400000 | Metric tons | -13.04% |
| 2011 | 348000 | Metric tons | -13.00% |
| 2012 | 471000 | Metric tons | 35.34% |
| 2013 | 226000 | Metric tons | -52.02% |
