Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 36623 | Metric tons | NA |
| 2006 | 30356 | Metric tons | -17.11% |
| 2007 | 42385 | Metric tons | 39.63% |
| 2008 | 49474 | Metric tons | 16.73% |
| 2009 | 27078 | Metric tons | -45.27% |
| 2010 | 36486 | Metric tons | 34.74% |
| 2011 | 31260 | Metric tons | -14.32% |
| 2012 | 25594 | Metric tons | -18.13% |
| 2013 | 30000 | Metric tons | 17.21% |
