Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1653 | Thousand metric tons | NA |
| 2003 | 1694 | Thousand metric tons | 2.48 % |
| 2004 | 2391 | Thousand metric tons | 41.15 % |
| 2005 | 2623.19995117188 | Thousand metric tons | 9.71 % |
| 2006 | 2883.80004882813 | Thousand metric tons | 9.93 % |
| 2007 | 3152.30004882813 | Thousand metric tons | 9.31 % |
| 2008 | 3200 | Thousand metric tons | 1.51 % |
