Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 300000 | Metric tons | NA |
| 2004 | 300000 | Metric tons | 0.00% |
| 2005 | 300000 | Metric tons | 0.00% |
| 2006 | 300000 | Metric tons | 0.00% |
| 2007 | 300000 | Metric tons | 0.00% |
| 2008 | 300000 | Metric tons | 0.00% |
| 2009 | 195000 | Metric tons | -35.00% |
| 2010 | 185000 | Metric tons | -5.13% |
| 2011 | 211000 | Metric tons | 14.05% |
| 2012 | 210000 | Metric tons | -0.47% |
| 2013 | 210000 | Metric tons | 0.00% |
