Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 144859 | Metric tons | NA |
| 2004 | 155717 | Metric tons | 7.50% |
| 2005 | 150000 | Metric tons | -3.67% |
| 2006 | 150000 | Metric tons | 0.00% |
| 2007 | 150000 | Metric tons | 0.00% |
| 2008 | 150000 | Metric tons | 0.00% |
| 2009 | 150000 | Metric tons | 0.00% |
| 2010 | 150000 | Metric tons | 0.00% |
| 2011 | 150000 | Metric tons | 0.00% |
| 2012 | 160180 | Metric tons | 6.79% |
| 2013 | 158386 | Metric tons | -1.12% |
