Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1493.41296386719 | Thousand metric tons | NA |
| 2004 | 1438.43298339844 | Thousand metric tons | -3.68% |
| 2005 | 1533.34594726563 | Thousand metric tons | 6.60% |
| 2006 | 1515.45202636719 | Thousand metric tons | -1.17% |
| 2007 | 1510.45495605469 | Thousand metric tons | -0.33% |
| 2008 | 1566.50695800781 | Thousand metric tons | 3.71% |
| 2009 | 2290.58911132813 | Thousand metric tons | 46.22% |
| 2010 | 2539.337890625 | Thousand metric tons | 10.86% |
| 2011 | 2668.22607421875 | Thousand metric tons | 5.08% |
| 2012 | 2626.55810546875 | Thousand metric tons | -1.56% |
| 2013 | 2650 | Thousand metric tons | 0.89% |
