Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 204000 | Metric tons | NA |
| 2010 | 160000 | Metric tons | -21.57% |
| 2011 | 240000 | Metric tons | 50.00% |
| 2012 | 225000 | Metric tons | -6.25% |
| 2013 | 175000 | Metric tons | -22.22% |
