Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 11.7930002212524 | Thousand metric tons | NA |
| 2004 | 6.72300004959106 | Thousand metric tons | -42.99 % |
| 2005 | 9.51799964904785 | Thousand metric tons | 41.57 % |
| 2006 | 11.0690002441406 | Thousand metric tons | 16.30 % |
| 2007 | 8.64500045776367 | Thousand metric tons | -21.90 % |
| 2008 | 5.44299983978271 | Thousand metric tons | -37.04 % |
| 2009 | 3.61199998855591 | Thousand metric tons | -33.64 % |
