Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2311 | Thousand metric tons | NA |
| 2004 | 2249 | Thousand metric tons | -2.68% |
| 2005 | 2671 | Thousand metric tons | 18.76% |
| 2006 | 3231 | Thousand metric tons | 20.97% |
| 2007 | 3351.56298828125 | Thousand metric tons | 3.73% |
| 2008 | 3544.4140625 | Thousand metric tons | 5.75% |
| 2009 | 2306.15087890625 | Thousand metric tons | -34.94% |
| 2010 | 2904.81811523438 | Thousand metric tons | 25.96% |
| 2011 | 2863.44091796875 | Thousand metric tons | -1.42% |
| 2012 | 2150.40600585938 | Thousand metric tons | -24.90% |
| 2013 | 2106.60888671875 | Thousand metric tons | -2.04% |
