Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 8525 | Thousand metric tons | NA |
| 2003 | 8883 | Thousand metric tons | 4.20% |
| 2004 | 10297.4326171875 | Thousand metric tons | 15.92% |
| 2005 | 11463.5458984375 | Thousand metric tons | 11.32% |
| 2006 | 12657.529296875 | Thousand metric tons | 10.42% |
| 2007 | 13651.416015625 | Thousand metric tons | 7.85% |
| 2008 | 13473 | Thousand metric tons | -1.31% |
| 2009 | 11784 | Thousand metric tons | -12.54% |
| 2010 | 10870 | Thousand metric tons | -7.76% |
| 2011 | 11234 | Thousand metric tons | 3.35% |
| 2012 | 11560 | Thousand metric tons | 2.90% |
