Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1242094 | Metric tons | NA |
| 2004 | 1535228 | Metric tons | 23.60% |
| 2005 | 1620099 | Metric tons | 5.53% |
| 2006 | 1423144 | Metric tons | -12.16% |
| 2007 | 1135771 | Metric tons | -20.19% |
| 2008 | 1063176 | Metric tons | -6.39% |
| 2009 | 919000 | Metric tons | -13.56% |
