Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 196169 | Metric tons | NA |
| 2004 | 275607 | Metric tons | 40.49% |
| 2005 | 231184 | Metric tons | -16.12% |
| 2006 | 246000 | Metric tons | 6.41% |
| 2007 | 249495 | Metric tons | 1.42% |
| 2008 | 226590 | Metric tons | -9.18% |
| 2009 | 361217 | Metric tons | 59.41% |
| 2010 | 326275 | Metric tons | -9.67% |
| 2011 | 330000 | Metric tons | 1.14% |
| 2012 | 330000 | Metric tons | 0.00% |
