Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 1566.75695800781 | Thousand metric tons | NA |
| 2010 | 1570 | Thousand metric tons | 0.21% |
| 2011 | 1565 | Thousand metric tons | -0.32% |
| 2012 | 1199.5849609375 | Thousand metric tons | -23.35% |
| 2013 | 1200.65002441406 | Thousand metric tons | 0.09% |
