Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2311 | Thousand metric tons | NA |
| 2004 | 2249 | Thousand metric tons | -2.68 % |
| 2005 | 2671 | Thousand metric tons | 18.76 % |
| 2006 | 3231 | Thousand metric tons | 20.97 % |
| 2007 | 3351.56298828125 | Thousand metric tons | 3.73 % |
| 2008 | 3544.4140625 | Thousand metric tons | 5.75 % |
| 2009 | 2306.14990234375 | Thousand metric tons | -34.94 % |
