Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 69091 | Metric tons | NA |
| 2010 | 75380 | Metric tons | 9.10 % |
| 2011 | 79207 | Metric tons | 5.08 % |
| 2012 | 80000 | Metric tons | 1.00 % |
| 2013 | 76000 | Metric tons | -5.00 % |
