Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 585 | Thousand metric tons | NA |
| 2010 | 600 | Thousand metric tons | 2.56% |
| 2011 | 650 | Thousand metric tons | 8.33% |
| 2012 | 700 | Thousand metric tons | 7.69% |
| 2013 | 720 | Thousand metric tons | 2.86% |
