Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 650000 | Metric tons | NA |
| 2004 | 650000 | Metric tons | 0.00% |
| 2005 | 650000 | Metric tons | 0.00% |
| 2006 | 650000 | Metric tons | 0.00% |
| 2007 | 810000 | Metric tons | 24.62% |
| 2008 | 901000 | Metric tons | 11.23% |
| 2009 | 957639 | Metric tons | 6.29% |
