Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 560 | Thousand metric tons | NA |
| 2004 | 683 | Thousand metric tons | 21.96% |
| 2005 | 722 | Thousand metric tons | 5.71% |
| 2006 | 861 | Thousand metric tons | 19.25% |
| 2007 | 890 | Thousand metric tons | 3.37% |
| 2008 | 947.7509765625 | Thousand metric tons | 6.49% |
| 2009 | 1009.77197265625 | Thousand metric tons | 6.54% |
| 2010 | 1400 | Thousand metric tons | 38.65% |
| 2011 | 1800 | Thousand metric tons | 28.57% |
| 2012 | 1820 | Thousand metric tons | 1.11% |
| 2013 | 1864 | Thousand metric tons | 2.42% |
