Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 533.617004394531 | Thousand metric tons | NA |
| 2004 | 631.401977539063 | Thousand metric tons | 18.32 % |
| 2005 | 531.890991210938 | Thousand metric tons | -15.76 % |
| 2006 | 512.276977539063 | Thousand metric tons | -3.69 % |
| 2007 | 719.221008300781 | Thousand metric tons | 40.40 % |
| 2008 | 1466.90405273438 | Thousand metric tons | 103.96 % |
| 2009 | 161.115005493164 | Thousand metric tons | -89.02 % |
