Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1026 | Thousand metric tons | NA |
| 2003 | 1186 | Thousand metric tons | 15.59% |
| 2004 | 1280.90002441406 | Thousand metric tons | 8.00% |
| 2005 | 1366 | Thousand metric tons | 6.64% |
| 2006 | 1431.90002441406 | Thousand metric tons | 4.82% |
| 2007 | 1513 | Thousand metric tons | 5.66% |
| 2008 | 1756 | Thousand metric tons | 16.06% |
| 2009 | 1941 | Thousand metric tons | 10.54% |
| 2010 | 2312 | Thousand metric tons | 19.11% |
| 2011 | 2409 | Thousand metric tons | 4.20% |
| 2012 | 2581 | Thousand metric tons | 7.14% |
