Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2009 | 5395 | Thousand metric tons | NA |
| 2010 | 4908 | Thousand metric tons | -9.03% |
| 2011 | 5938 | Thousand metric tons | 20.99% |
| 2012 | 6189.44580078125 | Thousand metric tons | 4.23% |
| 2013 | 6200 | Thousand metric tons | 0.17% |
