Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 6850 | Thousand metric tons | NA |
| 2003 | 7300 | Thousand metric tons | 6.57% |
| 2004 | 29000 | Thousand metric tons | 297.26% |
| 2005 | 32000 | Thousand metric tons | 10.34% |
| 2006 | 42000 | Thousand metric tons | 31.25% |
| 2007 | 48000 | Thousand metric tons | 14.29% |
| 2008 | 46000 | Thousand metric tons | -4.17% |
| 2009 | 126000 | Thousand metric tons | 173.91% |
| 2010 | 126000 | Thousand metric tons | 0.00% |
| 2011 | 127000 | Thousand metric tons | 0.79% |
| 2012 | 128000 | Thousand metric tons | 0.79% |
| 2013 | 129000 | Thousand metric tons | 0.78% |
