Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 460000 | Metric tons | NA |
| 2004 | 492000 | Metric tons | 6.96 % |
| 2005 | 542000 | Metric tons | 10.16 % |
| 2006 | 550000 | Metric tons | 1.48 % |
| 2007 | 550000 | Metric tons | 0.00 % |
| 2008 | 550000 | Metric tons | 0.00 % |
| 2009 | 500000 | Metric tons | -9.09 % |
