Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5692 | Thousand metric tons | NA |
| 2004 | 6077 | Thousand metric tons | 6.76% |
| 2005 | 5632 | Thousand metric tons | -7.32% |
| 2006 | 6266.0361328125 | Thousand metric tons | 11.26% |
| 2007 | 6261.3759765625 | Thousand metric tons | -0.07% |
