Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 878000 | Metric tons | NA |
| 2004 | 923000 | Metric tons | 5.13% |
| 2005 | 925000 | Metric tons | 0.22% |
| 2006 | 925000 | Metric tons | 0.00% |
| 2007 | 1025000 | Metric tons | 10.81% |
| 2008 | 1017000 | Metric tons | -0.78% |
| 2009 | 1000000 | Metric tons | -1.67% |
| 2010 | 995174 | Metric tons | -0.48% |
| 2011 | 1031880 | Metric tons | 3.69% |
| 2012 | 1041000 | Metric tons | 0.88% |
| 2013 | 1050000 | Metric tons | 0.86% |
