Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 1830 | Thousand metric tons | NA |
| 2010 | 2146 | Thousand metric tons | 17.27% |
| 2011 | 2547 | Thousand metric tons | 18.69% |
| 2012 | 3042 | Thousand metric tons | 19.43% |
| 2013 | 3501.5 | Thousand metric tons | 15.11% |
