Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2400000 | Metric tons | NA |
| 2004 | 2200000 | Metric tons | -8.33% |
| 2005 | 2300000 | Metric tons | 4.55% |
| 2006 | 2400000 | Metric tons | 4.35% |
| 2007 | 2000000 | Metric tons | -16.67% |
| 2008 | 2200000 | Metric tons | 10.00% |
| 2009 | 2300000 | Metric tons | 4.55% |
| 2010 | 2000000 | Metric tons | -13.04% |
| 2011 | 2100000 | Metric tons | 5.00% |
| 2012 | 2200000 | Metric tons | 4.76% |
| 2013 | 2200000 | Metric tons | 0.00% |
