Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2011 | 0.689999997615814 | Thousand metric tons | NA |
| 2012 | 0.699999988079071 | Thousand metric tons | 1.45% |
| 2013 | 0.699999988079071 | Thousand metric tons | 0.00% |
