Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 14000 | Metric tons, gross weight | NA |
| 2003 | 37000 | Metric tons, gross weight | 164.29% |
| 2004 | 26000 | Metric tons, gross weight | -29.73% |
| 2005 | 21654 | Metric tons, gross weight | -16.72% |
| 2006 | 28772 | Metric tons, gross weight | 32.87% |
| 2007 | 15476 | Metric tons, gross weight | -46.21% |
| 2008 | 27094 | Metric tons, gross weight | 75.07% |
| 2009 | 14087 | Metric tons, gross weight | -48.01% |
| 2010 | 56823 | Metric tons, gross weight | 303.37% |
| 2011 | 64128 | Metric tons, gross weight | 12.86% |
| 2012 | 18300 | Metric tons, gross weight | -71.46% |
