Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1076.14196777344 | Thousand metric tons | NA |
| 2004 | 595 | Thousand metric tons | -44.71% |
| 2005 | 791 | Thousand metric tons | 32.94% |
| 2006 | 931.10302734375 | Thousand metric tons | 17.71% |
| 2007 | 1000 | Thousand metric tons | 7.40% |
| 2008 | 1000 | Thousand metric tons | 0.00% |
| 2009 | 1163.80297851563 | Thousand metric tons | 16.38% |
| 2010 | 1119.4169921875 | Thousand metric tons | -3.81% |
| 2011 | 1379 | Thousand metric tons | 23.19% |
| 2012 | 1380 | Thousand metric tons | 0.07% |
| 2013 | 1380 | Thousand metric tons | 0.00% |
