Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 738 | Thousand metric tons | NA |
| 2004 | 866.073974609375 | Thousand metric tons | 17.35% |
| 2005 | 846.213012695313 | Thousand metric tons | -2.29% |
| 2006 | 931.013977050781 | Thousand metric tons | 10.02% |
| 2007 | 914.335021972656 | Thousand metric tons | -1.79% |
| 2008 | 811 | Thousand metric tons | -11.30% |
| 2009 | 809 | Thousand metric tons | -0.25% |
| 2010 | 807 | Thousand metric tons | -0.25% |
| 2011 | 809 | Thousand metric tons | 0.25% |
| 2012 | 665 | Thousand metric tons | -17.80% |
| 2013 | 822 | Thousand metric tons | 23.61% |
