Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 701.864990234375 | Thousand metric tons | NA |
| 2006 | 768.690002441406 | Thousand metric tons | 9.52% |
| 2007 | 827.719970703125 | Thousand metric tons | 7.68% |
| 2008 | 885.059997558594 | Thousand metric tons | 6.93% |
| 2009 | 798.179992675781 | Thousand metric tons | -9.82% |
| 2010 | 881.224975585938 | Thousand metric tons | 10.40% |
| 2011 | 958.231018066406 | Thousand metric tons | 8.74% |
| 2012 | 1000 | Thousand metric tons | 4.36% |
| 2013 | 1000 | Thousand metric tons | 0.00% |
