Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1600 | Thousand metric tons | NA |
| 2004 | 1710 | Thousand metric tons | 6.88% |
| 2005 | 1349 | Thousand metric tons | -21.11% |
| 2006 | 1277 | Thousand metric tons | -5.34% |
| 2007 | 1840 | Thousand metric tons | 44.09% |
| 2008 | 1957 | Thousand metric tons | 6.36% |
| 2009 | 2388 | Thousand metric tons | 22.02% |
| 2010 | 2390 | Thousand metric tons | 0.08% |
| 2011 | 2876 | Thousand metric tons | 20.33% |
| 2012 | 2900 | Thousand metric tons | 0.83% |
