Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 531.991027832031 | Thousand metric tons | NA |
| 2004 | 531.6259765625 | Thousand metric tons | -0.07% |
| 2005 | 750.710021972656 | Thousand metric tons | 41.21% |
| 2006 | 872.388000488281 | Thousand metric tons | 16.21% |
| 2007 | 865.047973632813 | Thousand metric tons | -0.84% |
| 2008 | 871.658020019531 | Thousand metric tons | 0.76% |
| 2009 | 847.737976074219 | Thousand metric tons | -2.74% |
| 2010 | 850.700012207031 | Thousand metric tons | 0.35% |
| 2011 | 881.309997558594 | Thousand metric tons | 3.60% |
| 2012 | 890.216979980469 | Thousand metric tons | 1.01% |
| 2013 | 912.700012207031 | Thousand metric tons | 2.53% |
