Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 640 | Thousand metric tons | NA |
| 2004 | 640 | Thousand metric tons | 0.00 % |
| 2005 | 650 | Thousand metric tons | 1.56 % |
| 2006 | 650 | Thousand metric tons | 0.00 % |
| 2007 | 1725 | Thousand metric tons | 165.38 % |
| 2008 | 1612.42797851563 | Thousand metric tons | -6.53 % |
| 2009 | 1750 | Thousand metric tons | 8.53 % |
