Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 136633 | Metric tons | NA |
| 2004 | 133829 | Metric tons | -2.05% |
| 2005 | 156935 | Metric tons | 17.27% |
| 2006 | 260000 | Metric tons | 65.67% |
| 2007 | 270000 | Metric tons | 3.85% |
| 2008 | 270000 | Metric tons | 0.00% |
| 2009 | 522832 | Metric tons | 93.64% |
| 2010 | 545585 | Metric tons | 4.35% |
| 2011 | 702673 | Metric tons | 28.79% |
| 2012 | 887600 | Metric tons | 26.32% |
| 2013 | 1075949 | Metric tons | 21.22% |
