Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 798.799987792969 | Thousand metric tons | NA |
| 2004 | 861.799987792969 | Thousand metric tons | 7.89% |
| 2005 | 942.400024414063 | Thousand metric tons | 9.35% |
| 2006 | 1105.09997558594 | Thousand metric tons | 17.26% |
| 2007 | 1221.80004882813 | Thousand metric tons | 10.56% |
| 2008 | 1307.5 | Thousand metric tons | 7.01% |
| 2009 | 1598 | Thousand metric tons | 22.22% |
| 2010 | 1607 | Thousand metric tons | 0.56% |
| 2011 | 1667 | Thousand metric tons | 3.73% |
| 2012 | 1700 | Thousand metric tons | 1.98% |
| 2013 | 1703 | Thousand metric tons | 0.18% |
