Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 40 | Thousand metric tons | NA |
| 2004 | 525 | Thousand metric tons | 1,212.50% |
| 2005 | 600 | Thousand metric tons | 14.29% |
| 2006 | 660 | Thousand metric tons | 10.00% |
| 2007 | 720 | Thousand metric tons | 9.09% |
| 2008 | 690 | Thousand metric tons | -4.17% |
| 2009 | 790 | Thousand metric tons | 14.49% |
| 2010 | 890 | Thousand metric tons | 12.66% |
| 2011 | 860 | Thousand metric tons | -3.37% |
| 2012 | 970 | Thousand metric tons | 12.79% |
| 2013 | 950 | Thousand metric tons | -2.06% |
