Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1983 | Thousand metric tons | NA |
| 2004 | 1957 | Thousand metric tons | -1.31% |
| 2005 | 1962 | Thousand metric tons | 0.26% |
| 2006 | 2029 | Thousand metric tons | 3.41% |
| 2007 | 2227 | Thousand metric tons | 9.76% |
