Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1701 | Thousand metric tons | NA |
| 2004 | 1967 | Thousand metric tons | 15.64% |
| 2005 | 2266 | Thousand metric tons | 15.20% |
| 2006 | 2416 | Thousand metric tons | 6.62% |
| 2007 | 2400 | Thousand metric tons | -0.66% |
