Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 48.4000015258789 | Thousand metric tons | NA |
| 2004 | 60.0800018310547 | Thousand metric tons | 24.13% |
| 2005 | 65.3499984741211 | Thousand metric tons | 8.77% |
| 2006 | 58.7050018310547 | Thousand metric tons | -10.17% |
| 2007 | 86.4609985351563 | Thousand metric tons | 47.28% |
| 2008 | 48.5750007629395 | Thousand metric tons | -43.82% |
| 2009 | 43.4580001831055 | Thousand metric tons | -10.53% |
| 2010 | 113.231002807617 | Thousand metric tons | 160.55% |
| 2011 | 109.346000671387 | Thousand metric tons | -3.43% |
| 2012 | 73.0640029907227 | Thousand metric tons | -33.18% |
| 2013 | 101.702003479004 | Thousand metric tons | 39.20% |
