Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 28.5 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 32.2999992370605 | Thousand metric tons of contained nitrogen | 13.33% |
| 2005 | 32 | Thousand metric tons of contained nitrogen | -0.93% |
| 2006 | 32 | Thousand metric tons of contained nitrogen | 0.00% |
| 2007 | 32 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 30 | Thousand metric tons of contained nitrogen | -6.25% |
| 2009 | 30 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 30 | Thousand metric tons of contained nitrogen | 0.00% |
| 2011 | 30 | Thousand metric tons of contained nitrogen | 0.00% |
| 2012 | 30 | Thousand metric tons of contained nitrogen | 0.00% |
