Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 480.161987304688 | Thousand metric tons | NA |
| 2004 | 553.60498046875 | Thousand metric tons | 15.30% |
| 2005 | 461.180999755859 | Thousand metric tons | -16.69% |
| 2006 | 1436.77600097656 | Thousand metric tons | 211.54% |
| 2007 | 2227 | Thousand metric tons | 55.00% |
| 2008 | 1756.708984375 | Thousand metric tons | -21.12% |
| 2009 | 3.53600001335144 | Thousand metric tons | -99.80% |
| 2010 | 3.6029999256134 | Thousand metric tons | 1.89% |
| 2011 | 3.6029999256134 | Thousand metric tons | 0.00% |
| 2012 | 4.18400001525879 | Thousand metric tons | 16.13% |
| 2013 | 4.19399976730347 | Thousand metric tons | 0.24% |
