Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 131705 | Metric tons | NA |
| 2003 | 131600 | Metric tons | -0.08 % |
| 2004 | 132000 | Metric tons | 0.30 % |
| 2005 | 126547 | Metric tons | -4.13 % |
| 2006 | 129693 | Metric tons | 2.49 % |
| 2007 | 130160 | Metric tons | 0.36 % |
| 2008 | 129500 | Metric tons | -0.51 % |
