Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 13000 | Thousand metric tons | NA |
| 2004 | 17000 | Thousand metric tons | 30.77% |
| 2005 | 22000 | Thousand metric tons | 29.41% |
| 2006 | 27000 | Thousand metric tons | 22.73% |
| 2007 | 30000 | Thousand metric tons | 11.11% |
| 2008 | 35000 | Thousand metric tons | 16.67% |
| 2009 | 40000 | Thousand metric tons | 14.29% |
