Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 33.2099990844727 | Thousand metric tons | NA |
| 2004 | 46.9000015258789 | Thousand metric tons | 41.22% |
| 2005 | 229 | Thousand metric tons | 388.27% |
| 2006 | 392 | Thousand metric tons | 71.18% |
| 2007 | 628 | Thousand metric tons | 60.20% |
| 2008 | 650 | Thousand metric tons | 3.50% |
| 2009 | 298 | Thousand metric tons | -54.15% |
| 2010 | 150 | Thousand metric tons | -49.66% |
| 2011 | 88.447998046875 | Thousand metric tons | -41.03% |
| 2012 | 88 | Thousand metric tons | -0.51% |
| 2013 | 90 | Thousand metric tons | 2.27% |
