Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 5680 | Thousand metric tons | NA |
| 2003 | 5992 | Thousand metric tons | 5.49 % |
| 2004 | 6238.583984375 | Thousand metric tons | 4.12 % |
| 2005 | 7032.10009765625 | Thousand metric tons | 12.72 % |
| 2006 | 8252.765625 | Thousand metric tons | 17.36 % |
| 2007 | 10061.34765625 | Thousand metric tons | 21.91 % |
| 2008 | 10702.98046875 | Thousand metric tons | 6.38 % |
