Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2006 | 149279 | Metric tons | NA |
| 2007 | 114482 | Metric tons | -23.31% |
| 2008 | 124304 | Metric tons | 8.58% |
| 2009 | 132470 | Metric tons | 6.57% |
