Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 91266 | Thousand metric tons | NA |
| 2003 | 94329 | Thousand metric tons | 3.36% |
| 2004 | 99014.5859375 | Thousand metric tons | 4.97% |
| 2005 | 100902.7109375 | Thousand metric tons | 1.91% |
| 2006 | 99712.375 | Thousand metric tons | -1.18% |
| 2007 | 96849.6484375 | Thousand metric tons | -2.87% |
| 2008 | 87610 | Thousand metric tons | -9.54% |
| 2009 | 64843 | Thousand metric tons | -25.99% |
| 2010 | 67202 | Thousand metric tons | 3.64% |
| 2011 | 68639 | Thousand metric tons | 2.14% |
| 2012 | 74934 | Thousand metric tons | 9.17% |
