Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 77.0999984741211 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 60.5999984741211 | Thousand metric tons of contained nitrogen | -21.40% |
| 2005 | 63 | Thousand metric tons of contained nitrogen | 3.96% |
| 2006 | 62 | Thousand metric tons of contained nitrogen | -1.59% |
| 2007 | 62 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 73.8679962158203 | Thousand metric tons of contained nitrogen | 19.14% |
| 2009 | 68.3789978027344 | Thousand metric tons of contained nitrogen | -7.43% |
| 2010 | 78.379997253418 | Thousand metric tons of contained nitrogen | 14.63% |
| 2011 | 72.3519973754883 | Thousand metric tons of contained nitrogen | -7.69% |
| 2012 | 72 | Thousand metric tons of contained nitrogen | -0.49% |
