Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 46309.62890625 | Thousand metric tons | NA |
| 2004 | 47520.87109375 | Thousand metric tons | 2.62% |
| 2005 | 47820.03515625 | Thousand metric tons | 0.63% |
| 2006 | 48455.453125 | Thousand metric tons | 1.33% |
| 2007 | 51517.30859375 | Thousand metric tons | 6.32% |
