Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 701.864990234375 | Thousand metric tons | NA |
| 2006 | 768.690002441406 | Thousand metric tons | 9.52 % |
| 2007 | 827.719970703125 | Thousand metric tons | 7.68 % |
| 2008 | 885.059997558594 | Thousand metric tons | 6.93 % |
| 2009 | 803.530029296875 | Thousand metric tons | -9.21 % |