Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2618 | Thousand metric tons | NA |
| 2003 | 2237 | Thousand metric tons | -14.55% |
| 2004 | 2400 | Thousand metric tons | 7.29% |
| 2005 | 1590 | Thousand metric tons | -33.75% |
| 2006 | 1600 | Thousand metric tons | 0.63% |
| 2007 | 2184.72900390625 | Thousand metric tons | 36.55% |
| 2008 | 178 | Thousand metric tons | -91.85% |
| 2009 | 195 | Thousand metric tons | 9.55% |
| 2010 | 256 | Thousand metric tons | 31.28% |
| 2011 | 250 | Thousand metric tons | -2.34% |
| 2012 | 250 | Thousand metric tons | 0.00% |
