Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 170 | Thousand metric tons | NA |
| 2004 | 237 | Thousand metric tons | 39.41 % |
| 2005 | 224 | Thousand metric tons | -5.49 % |
| 2006 | 179 | Thousand metric tons | -20.09 % |
| 2007 | 140.74299621582 | Thousand metric tons | -21.37 % |
| 2008 | 172.259002685547 | Thousand metric tons | 22.39 % |
| 2009 | 185.061996459961 | Thousand metric tons | 7.43 % |
