Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 8525 | Thousand metric tons | NA |
| 2003 | 8883 | Thousand metric tons | 4.20 % |
| 2004 | 10297.4326171875 | Thousand metric tons | 15.92 % |
| 2005 | 11463.5458984375 | Thousand metric tons | 11.32 % |
| 2006 | 12657.529296875 | Thousand metric tons | 10.42 % |
| 2007 | 13651.416015625 | Thousand metric tons | 7.85 % |
| 2008 | 13341.0615234375 | Thousand metric tons | -2.27 % |
