Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 98 | Thousand metric tons | NA |
| 2004 | 119 | Thousand metric tons | 21.43 % |
| 2005 | 124 | Thousand metric tons | 4.20 % |
| 2006 | 136 | Thousand metric tons | 9.68 % |
| 2007 | 148 | Thousand metric tons | 8.82 % |
| 2008 | 145.419998168945 | Thousand metric tons | -1.74 % |
| 2009 | 145.5 | Thousand metric tons | 0.06 % |
| 2010 | 150 | Thousand metric tons | 3.09 % |
| 2011 | 45 | Thousand metric tons | -70.00 % |
| 2012 | 68 | Thousand metric tons | 51.11 % |
