Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 137596 | Metric tons | NA |
| 2004 | 138000 | Metric tons | 0.29% |
| 2005 | 166569 | Metric tons | 20.70% |
| 2006 | 159447 | Metric tons | -4.28% |
| 2007 | 153409 | Metric tons | -3.79% |
| 2008 | 154577 | Metric tons | 0.76% |
| 2009 | 111388 | Metric tons | -27.94% |
| 2010 | 138367 | Metric tons | 24.22% |
| 2011 | 132018 | Metric tons | -4.59% |
| 2012 | 134665 | Metric tons | 2.01% |
| 2013 | 135000 | Metric tons | 0.25% |
