Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 4699.73876953125 | Thousand metric tons | NA |
| 2004 | 4705.33984375 | Thousand metric tons | 0.12 % |
| 2005 | 4548.615234375 | Thousand metric tons | -3.33 % |
| 2006 | 4593.076171875 | Thousand metric tons | 0.98 % |
| 2007 | 4314 | Thousand metric tons | -6.08 % |
| 2008 | 3664 | Thousand metric tons | -15.07 % |
| 2009 | 3500 | Thousand metric tons | -4.48 % |
