Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 119648 | Metric tons | NA |
| 2004 | 134504 | Metric tons | 12.42 % |
| 2005 | 157179 | Metric tons | 16.86 % |
| 2006 | 161993 | Metric tons | 3.06 % |
| 2007 | 184041 | Metric tons | 13.61 % |
| 2008 | 170000 | Metric tons | -7.63 % |
| 2009 | 150000 | Metric tons | -11.76 % |
