Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2006 | 46.0699996948242 | Thousand metric tons | NA |
| 2007 | 69.5479965209961 | Thousand metric tons | 50.96% |
| 2008 | 61.2910003662109 | Thousand metric tons | -11.87% |
| 2009 | 30.4090003967285 | Thousand metric tons | -50.39% |
| 2010 | 34.4370002746582 | Thousand metric tons | 13.25% |
| 2011 | 36 | Thousand metric tons | 4.54% |
| 2012 | 37 | Thousand metric tons | 2.78% |
| 2013 | 38 | Thousand metric tons | 2.70% |
