Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 161.100006103516 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 115.199996948242 | Thousand metric tons of contained nitrogen | -28.49% |
| 2005 | 120 | Thousand metric tons of contained nitrogen | 4.17% |
| 2006 | 120 | Thousand metric tons of contained nitrogen | 0.00% |
| 2007 | 120 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 165 | Thousand metric tons of contained nitrogen | 37.50% |
| 2009 | 180 | Thousand metric tons of contained nitrogen | 9.09% |
| 2010 | 169 | Thousand metric tons of contained nitrogen | -6.11% |
| 2011 | 85 | Thousand metric tons of contained nitrogen | -49.70% |
| 2012 | 50 | Thousand metric tons of contained nitrogen | -41.18% |
