Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 79085 | Metric tons | NA |
| 2003 | 124410 | Metric tons | 57.31% |
| 2004 | 118451 | Metric tons | -4.79% |
| 2005 | 173635 | Metric tons | 46.59% |
| 2006 | 222101 | Metric tons | 27.91% |
| 2007 | 192277 | Metric tons | -13.43% |
| 2008 | 239528 | Metric tons | 24.57% |
| 2009 | 197482 | Metric tons | -17.55% |
| 2010 | 295000 | Metric tons | 49.38% |
| 2011 | 421391 | Metric tons | 42.84% |
| 2012 | 456921 | Metric tons | 8.43% |
| 2013 | 421000 | Metric tons | -7.86% |
