Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 352.559997558594 | Thousand metric tons | NA |
| 2004 | 353.834991455078 | Thousand metric tons | 0.36 % |
| 2005 | 360.161010742188 | Thousand metric tons | 1.79 % |
| 2006 | 374.209991455078 | Thousand metric tons | 3.90 % |
| 2007 | 386.597991943359 | Thousand metric tons | 3.31 % |
| 2008 | 513.414978027344 | Thousand metric tons | 32.80 % |
| 2009 | 404.903991699219 | Thousand metric tons | -21.14 % |
