Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 2034 | Thousand metric tons | NA |
| 2010 | 2248 | Thousand metric tons | 10.52% |
| 2011 | 2343 | Thousand metric tons | 4.23% |
| 2012 | 2080 | Thousand metric tons | -11.22% |
| 2013 | 2200 | Thousand metric tons | 5.77% |
