Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 140528 | Metric tons | NA |
| 2004 | 193046 | Metric tons | 37.37% |
| 2005 | 261888 | Metric tons | 35.66% |
| 2006 | 260000 | Metric tons | -0.72% |
| 2007 | 254084 | Metric tons | -2.28% |
| 2008 | 240000 | Metric tons | -5.54% |
| 2009 | 387437 | Metric tons | 61.43% |
| 2010 | 350208 | Metric tons | -9.61% |
| 2011 | 377398 | Metric tons | 7.76% |
| 2012 | 400000 | Metric tons | 5.99% |
| 2013 | 400000 | Metric tons | 0.00% |
