Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 200 | Thousand metric tons | NA |
| 2004 | 260.5 | Thousand metric tons | 30.25% |
| 2005 | 392.239990234375 | Thousand metric tons | 50.57% |
| 2006 | 416.304992675781 | Thousand metric tons | 6.14% |
| 2007 | 502.486999511719 | Thousand metric tons | 20.70% |
| 2008 | 555.122009277344 | Thousand metric tons | 10.47% |
| 2009 | 556.088989257813 | Thousand metric tons | 0.17% |
| 2010 | 662.630981445313 | Thousand metric tons | 19.16% |
| 2011 | 833.734008789063 | Thousand metric tons | 25.82% |
| 2012 | 862.017028808594 | Thousand metric tons | 3.39% |
| 2013 | 860 | Thousand metric tons | -0.23% |
