Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 27500 | Thousand metric tons | NA |
| 2004 | 29700 | Thousand metric tons | 8.00 % |
| 2005 | 30600 | Thousand metric tons | 3.03 % |
| 2006 | 28900 | Thousand metric tons | -5.56 % |
| 2007 | 30100 | Thousand metric tons | 4.15 % |
| 2008 | 30400 | Thousand metric tons | 1.00 % |
| 2009 | 24600 | Thousand metric tons | -19.08 % |
