Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 13444.423828125 | Thousand metric tons | NA |
| 2004 | 13296.4814453125 | Thousand metric tons | -1.10% |
| 2005 | 14116 | Thousand metric tons | 6.16% |
| 2006 | 14865 | Thousand metric tons | 5.31% |
| 2007 | 14568 | Thousand metric tons | -2.00% |
| 2008 | 14363 | Thousand metric tons | -1.41% |
| 2009 | 7817.462890625 | Thousand metric tons | -45.57% |
