Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 493.200012207031 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 459.100006103516 | Thousand metric tons of contained nitrogen | -6.91% |
| 2005 | 460 | Thousand metric tons of contained nitrogen | 0.20% |
| 2006 | 480 | Thousand metric tons of contained nitrogen | 4.35% |
| 2007 | 480 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 510 | Thousand metric tons of contained nitrogen | 6.25% |
| 2009 | 510 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 470 | Thousand metric tons of contained nitrogen | -7.84% |
| 2011 | 470 | Thousand metric tons of contained nitrogen | 0.00% |
| 2012 | 470 | Thousand metric tons of contained nitrogen | 0.00% |
