Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 780 | Thousand metric tons | NA |
| 2004 | 830 | Thousand metric tons | 6.41% |
| 2005 | 820 | Thousand metric tons | -1.20% |
| 2006 | 880 | Thousand metric tons | 7.32% |
| 2007 | 1200 | Thousand metric tons | 36.36% |
| 2008 | 1700 | Thousand metric tons | 41.67% |
| 2009 | 2100 | Thousand metric tons | 23.53% |
| 2010 | 2157 | Thousand metric tons | 2.71% |
| 2011 | 2230 | Thousand metric tons | 3.38% |
| 2012 | 2420 | Thousand metric tons | 8.52% |
