Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 950000 | Metric tons | NA |
| 2004 | 950000 | Metric tons | 0.00% |
| 2005 | 1124795 | Metric tons | 18.40% |
| 2006 | 1125000 | Metric tons | 0.02% |
| 2007 | 950000 | Metric tons | -15.56% |
| 2008 | 1500000 | Metric tons | 57.89% |
| 2009 | 926186 | Metric tons | -38.25% |
| 2010 | 1381643 | Metric tons | 49.18% |
| 2011 | 1188442 | Metric tons | -13.98% |
| 2012 | 1235105 | Metric tons | 3.93% |
| 2013 | 1000000 | Metric tons | -19.04% |
