Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 490 | Thousand metric tons | NA |
| 2004 | 836.297973632813 | Thousand metric tons | 70.67% |
| 2005 | 1073.28601074219 | Thousand metric tons | 28.34% |
| 2006 | 1202.81201171875 | Thousand metric tons | 12.07% |
| 2007 | 1226.53002929688 | Thousand metric tons | 1.97% |
| 2008 | 1200 | Thousand metric tons | -2.16% |
| 2009 | 1355.26000976563 | Thousand metric tons | 12.94% |
| 2010 | 1346.53503417969 | Thousand metric tons | -0.64% |
| 2011 | 1452.79699707031 | Thousand metric tons | 7.89% |
| 2012 | 1432.51696777344 | Thousand metric tons | -1.40% |
| 2013 | 1443 | Thousand metric tons | 0.73% |
