Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 16967 | Metric tons | NA |
| 2004 | 24353 | Metric tons | 43.53 % |
| 2005 | 24882 | Metric tons | 2.17 % |
| 2006 | 24645 | Metric tons | -0.95 % |
| 2007 | 32912 | Metric tons | 33.54 % |
| 2008 | 30504 | Metric tons | -7.32 % |
| 2009 | 30000 | Metric tons | -1.65 % |
