Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 222 | Thousand metric tons | NA |
| 2010 | 232 | Thousand metric tons | 4.50% |
| 2011 | 258 | Thousand metric tons | 11.21% |
| 2012 | 237 | Thousand metric tons | -8.14% |
| 2013 | 240 | Thousand metric tons | 1.27% |
