Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 145000 | Metric tons | NA |
| 2004 | 265000 | Metric tons | 82.76% |
| 2005 | 223000 | Metric tons | -15.85% |
| 2006 | 220000 | Metric tons | -1.35% |
| 2007 | 255000 | Metric tons | 15.91% |
| 2008 | 250000 | Metric tons | -1.96% |
| 2009 | 240000 | Metric tons | -4.00% |
| 2010 | 230000 | Metric tons | -4.17% |
| 2011 | 230000 | Metric tons | 0.00% |
| 2012 | 230000 | Metric tons | 0.00% |
| 2013 | 230000 | Metric tons | 0.00% |
