Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 250 | Thousand metric tons | NA |
| 2006 | 259.545013427734 | Thousand metric tons | 3.82% |
| 2007 | 572.023010253906 | Thousand metric tons | 120.39% |
| 2008 | 600 | Thousand metric tons | 4.89% |
| 2009 | 350 | Thousand metric tons | -41.67% |
| 2010 | 330 | Thousand metric tons | -5.71% |
| 2011 | 271 | Thousand metric tons | -17.88% |
| 2012 | 425 | Thousand metric tons | 56.83% |
| 2013 | 400 | Thousand metric tons | -5.88% |
