Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1283 | Thousand metric tons | NA |
| 2004 | 1188 | Thousand metric tons | -7.40% |
| 2005 | 1466.53295898438 | Thousand metric tons | 23.45% |
| 2006 | 1871.88696289063 | Thousand metric tons | 27.64% |
| 2007 | 2146.98608398438 | Thousand metric tons | 14.70% |
| 2008 | 2100 | Thousand metric tons | -2.19% |
| 2009 | 4499.15380859375 | Thousand metric tons | 114.25% |
| 2010 | 4022.43310546875 | Thousand metric tons | -10.60% |
| 2011 | 7020.6220703125 | Thousand metric tons | 74.54% |
| 2012 | 7085.3798828125 | Thousand metric tons | 0.92% |
| 2013 | 7969.39208984375 | Thousand metric tons | 12.48% |
