Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1293.92895507813 | Thousand metric tons | NA |
| 2004 | 587.655029296875 | Thousand metric tons | -54.58 % |
| 2005 | 718.320007324219 | Thousand metric tons | 22.23 % |
| 2006 | 861.846984863281 | Thousand metric tons | 19.98 % |
| 2007 | 844.070983886719 | Thousand metric tons | -2.06 % |
| 2008 | 495.847991943359 | Thousand metric tons | -41.26 % |
| 2009 | 600 | Thousand metric tons | 21.00 % |
