Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 166.36799621582 | Thousand metric tons | NA |
| 2004 | 117.169998168945 | Thousand metric tons | -29.57% |
| 2005 | 283.110992431641 | Thousand metric tons | 141.62% |
| 2006 | 469.122009277344 | Thousand metric tons | 65.70% |
| 2007 | 550 | Thousand metric tons | 17.24% |
