Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 46000 | Thousand metric tons | NA |
| 2010 | 43300 | Thousand metric tons | -5.87% |
| 2011 | 45000 | Thousand metric tons | 3.93% |
| 2012 | 37200 | Thousand metric tons | -17.33% |
| 2013 | 40300 | Thousand metric tons | 8.33% |
