Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 6834 | Thousand metric tons | NA |
| 2003 | 1901 | Thousand metric tons | -72.18 % |
| 2004 | 2500 | Thousand metric tons | 31.51 % |
| 2005 | 3000 | Thousand metric tons | 20.00 % |
| 2006 | 3500 | Thousand metric tons | 16.67 % |
| 2007 | 4500 | Thousand metric tons | 28.57 % |
| 2008 | 5500 | Thousand metric tons | 22.22 % |
