Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2081039 | Metric tons | NA |
| 2004 | 2381000 | Metric tons | 14.41% |
| 2005 | 2410000 | Metric tons | 1.22% |
| 2006 | 2455000 | Metric tons | 1.87% |
| 2007 | 2500000 | Metric tons | 1.83% |
