Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 400.602996826172 | Thousand metric tons | NA |
| 2004 | 594.190979003906 | Thousand metric tons | 48.32% |
| 2005 | 460.683013916016 | Thousand metric tons | -22.47% |
| 2006 | 459.644989013672 | Thousand metric tons | -0.23% |
| 2007 | 527.929016113281 | Thousand metric tons | 14.86% |
| 2008 | 583.473999023438 | Thousand metric tons | 10.52% |
| 2009 | 607.921020507813 | Thousand metric tons | 4.19% |
| 2010 | 503.609008789063 | Thousand metric tons | -17.16% |
| 2011 | 488.523010253906 | Thousand metric tons | -3.00% |
| 2012 | 444.486999511719 | Thousand metric tons | -9.01% |
| 2013 | 580.528015136719 | Thousand metric tons | 30.61% |
