Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 130000 | Metric tons | NA |
| 2004 | 150000 | Metric tons | 15.38% |
| 2005 | 180000 | Metric tons | 20.00% |
| 2006 | 180000 | Metric tons | 0.00% |
| 2007 | 190000 | Metric tons | 5.56% |
| 2008 | 200000 | Metric tons | 5.26% |
| 2009 | 210000 | Metric tons | 5.00% |
| 2010 | 200000 | Metric tons | -4.76% |
| 2011 | 200000 | Metric tons | 0.00% |
| 2012 | 190000 | Metric tons | -5.00% |
| 2013 | 180000 | Metric tons | -5.26% |
