Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 125 | Thousand metric tons | NA |
| 2003 | 110 | Thousand metric tons | -12.00% |
| 2004 | 108 | Thousand metric tons | -1.82% |
| 2005 | 113 | Thousand metric tons | 4.63% |
| 2006 | 151 | Thousand metric tons | 33.63% |
| 2007 | 157 | Thousand metric tons | 3.97% |
| 2008 | 165 | Thousand metric tons | 5.10% |
| 2009 | 360 | Thousand metric tons | 118.18% |
| 2010 | 435 | Thousand metric tons | 20.83% |
| 2011 | 534 | Thousand metric tons | 22.76% |
| 2012 | 776 | Thousand metric tons | 45.32% |
| 2013 | 550 | Thousand metric tons | -29.12% |
