Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1010 | Thousand metric tons | NA |
| 2003 | 1138 | Thousand metric tons | 12.67% |
| 2004 | 1276.41198730469 | Thousand metric tons | 12.16% |
| 2005 | 1439.95104980469 | Thousand metric tons | 12.81% |
| 2006 | 1636.07897949219 | Thousand metric tons | 13.62% |
| 2007 | 1738.64904785156 | Thousand metric tons | 6.27% |
| 2008 | 1985 | Thousand metric tons | 14.17% |
| 2009 | 2292 | Thousand metric tons | 15.47% |
| 2010 | 2414 | Thousand metric tons | 5.32% |
| 2011 | 2658 | Thousand metric tons | 10.11% |
| 2012 | 2714 | Thousand metric tons | 2.11% |
