Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 570.109985351563 | Thousand metric tons | NA |
| 2003 | 9.67500019073486 | Thousand metric tons | -98.30% |
| 2004 | 135.580001831055 | Thousand metric tons | 1,301.34% |
| 2005 | 230.945999145508 | Thousand metric tons | 70.34% |
| 2006 | 264.289001464844 | Thousand metric tons | 14.44% |
| 2007 | 1554.85998535156 | Thousand metric tons | 488.32% |
| 2008 | 2029.09997558594 | Thousand metric tons | 30.50% |
| 2009 | 1400.80004882813 | Thousand metric tons | -30.96% |
| 2010 | 969.93701171875 | Thousand metric tons | -30.76% |
| 2011 | 970 | Thousand metric tons | 0.01% |
| 2012 | 970 | Thousand metric tons | 0.00% |
