Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 55602 | Thousand metric tons | NA |
| 2004 | 56593 | Thousand metric tons | 1.78% |
| 2005 | 59959 | Thousand metric tons | 5.95% |
| 2006 | 61780 | Thousand metric tons | 3.04% |
| 2007 | 62398 | Thousand metric tons | 1.00% |
| 2008 | 61389 | Thousand metric tons | -1.62% |
| 2009 | 65231 | Thousand metric tons | 6.26% |
