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% |
