Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 251100 | Metric tons | NA |
| 2003 | 269000 | Metric tons | 7.13% |
| 2004 | 320300 | Metric tons | 19.07% |
| 2005 | 330000 | Metric tons | 3.03% |
| 2006 | 350000 | Metric tons | 6.06% |
| 2007 | 341000 | Metric tons | -2.57% |
| 2008 | 372000 | Metric tons | 9.09% |
| 2009 | 557000 | Metric tons | 49.73% |
| 2010 | 540000 | Metric tons | -3.05% |
| 2011 | 524000 | Metric tons | -2.96% |
| 2012 | 515000 | Metric tons | -1.72% |
