Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 413340 | Metric tons | NA |
| 2006 | 389471 | Metric tons | -5.77% |
| 2007 | 401204 | Metric tons | 3.01% |
| 2008 | 401210 | Metric tons | 0.00% |
| 2009 | 543959 | Metric tons | 35.58% |
| 2010 | 507085 | Metric tons | -6.78% |
| 2011 | 539745 | Metric tons | 6.44% |
| 2012 | 550000 | Metric tons | 1.90% |
| 2013 | 550000 | Metric tons | 0.00% |
