Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 900 | Thousand metric tons | NA |
| 2003 | 1130 | Thousand metric tons | 25.56 % |
| 2004 | 1315.93395996094 | Thousand metric tons | 16.45 % |
| 2005 | 1568.6240234375 | Thousand metric tons | 19.20 % |
| 2006 | 1676 | Thousand metric tons | 6.85 % |
| 2007 | 1800 | Thousand metric tons | 7.40 % |
| 2008 | 1820 | Thousand metric tons | 1.11 % |
