Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5445.51611328125 | Thousand metric tons | NA |
| 2004 | 5842 | Thousand metric tons | 7.28% |
| 2005 | 5900 | Thousand metric tons | 0.99% |
| 2006 | 5928 | Thousand metric tons | 0.47% |
| 2007 | 5500 | Thousand metric tons | -7.22% |
| 2008 | 5500 | Thousand metric tons | 0.00% |
| 2009 | 2500 | Thousand metric tons | -54.55% |
