Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5706.7998046875 | Thousand metric tons | NA |
| 2004 | 5836 | Thousand metric tons | 2.26% |
| 2005 | 5970 | Thousand metric tons | 2.30% |
| 2006 | 5952 | Thousand metric tons | -0.30% |
| 2007 | 6234 | Thousand metric tons | 4.74% |
| 2008 | 6697 | Thousand metric tons | 7.43% |
| 2009 | 6913.3251953125 | Thousand metric tons | 3.23% |
| 2010 | 7676.591796875 | Thousand metric tons | 11.04% |
| 2011 | 7700 | Thousand metric tons | 0.30% |
| 2012 | 8600 | Thousand metric tons | 11.69% |
