Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 559 | Thousand metric tons | NA |
| 2004 | 544 | Thousand metric tons | -2.68% |
| 2005 | 639 | Thousand metric tons | 17.46% |
| 2006 | 462 | Thousand metric tons | -27.70% |
| 2007 | 395 | Thousand metric tons | -14.50% |
| 2008 | 358 | Thousand metric tons | -9.37% |
| 2009 | 691 | Thousand metric tons | 93.02% |
| 2010 | 459 | Thousand metric tons | -33.57% |
| 2011 | 430 | Thousand metric tons | -6.32% |
| 2012 | 379 | Thousand metric tons | -11.86% |
| 2013 | 380 | Thousand metric tons | 0.26% |
