Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 32 | Thousand metric tons | NA |
| 2003 | 32 | Thousand metric tons | 0.00% |
| 2004 | 102.5 | Thousand metric tons | 220.31% |
| 2005 | 130.800003051758 | Thousand metric tons | 27.61% |
| 2006 | 186.199996948242 | Thousand metric tons | 42.35% |
| 2007 | 311.899993896484 | Thousand metric tons | 67.51% |
| 2008 | 300 | Thousand metric tons | -3.82% |
| 2009 | 94.4000015258789 | Thousand metric tons | -68.53% |
| 2010 | 99.8000030517578 | Thousand metric tons | 5.72% |
| 2011 | 100.540000915527 | Thousand metric tons | 0.74% |
| 2012 | 115.099998474121 | Thousand metric tons | 14.48% |
| 2013 | 120 | Thousand metric tons | 4.26% |
