Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2100 | Thousand metric tons | NA |
| 2003 | 2300 | Thousand metric tons | 9.52% |
| 2004 | 2300 | Thousand metric tons | 0.00% |
| 2005 | 2700 | Thousand metric tons | 17.39% |
| 2006 | 3300 | Thousand metric tons | 22.22% |
| 2007 | 4700 | Thousand metric tons | 42.42% |
| 2008 | 10000 | Thousand metric tons | 112.77% |
| 2009 | 10000 | Thousand metric tons | 0.00% |
| 2010 | 11000 | Thousand metric tons | 10.00% |
| 2011 | 12800 | Thousand metric tons | 16.36% |
| 2012 | 16400 | Thousand metric tons | 28.13% |
