Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 831146 | Metric tons | NA |
| 2004 | 850000 | Metric tons | 2.27% |
| 2005 | 925000 | Metric tons | 8.82% |
| 2006 | 950000 | Metric tons | 2.70% |
| 2007 | 930000 | Metric tons | -2.11% |
| 2008 | 900000 | Metric tons | -3.23% |
| 2009 | 932487 | Metric tons | 3.61% |
| 2010 | 798397 | Metric tons | -14.38% |
| 2011 | 471528 | Metric tons | -40.94% |
| 2012 | 1033568 | Metric tons | 119.20% |
| 2013 | 1100000 | Metric tons | 6.43% |
