Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1667.85095214844 | Thousand metric tons | NA |
| 2004 | 1371.96899414063 | Thousand metric tons | -17.74 % |
| 2005 | 1845.8330078125 | Thousand metric tons | 34.54 % |
| 2006 | 1917.65600585938 | Thousand metric tons | 3.89 % |
| 2007 | 2357.67407226563 | Thousand metric tons | 22.95 % |
| 2008 | 1681.26098632813 | Thousand metric tons | -28.69 % |
| 2009 | 1700 | Thousand metric tons | 1.11 % |
