Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 157 | Thousand metric tons | NA |
| 2003 | 174 | Thousand metric tons | 10.83 % |
| 2004 | 226 | Thousand metric tons | 29.89 % |
| 2005 | 213 | Thousand metric tons | -5.75 % |
| 2006 | 227 | Thousand metric tons | 6.57 % |
| 2007 | 291 | Thousand metric tons | 28.19 % |
| 2008 | 366 | Thousand metric tons | 25.77 % |
| 2009 | 360 | Thousand metric tons | -1.64 % |
