"In 2011, the estimated potential opium production amounted to 5,800 mt, an increase by 61% over 2010. As opium cultivation remained relatively stable between 2009 and 2011, the differences in opium production in those years were due to changes in per-hectare opium yield. 2009 was a year with high opium yields (56.1 kg/ha), while in 2010, major opium cultivation areas were affected by plant diseases, which led to a strong yield reduction (29.2 kg/ha). In 2011, opium yields were back to “normal” levels of 44.5 kg/ha. In 2011, the Southern region continued to produce most opium in Afghanistan, representing 85% of national production, followed by the Western region (12%)."

Source

"Afghanistan Opium Survey 2011," United Nations Office on Drugs and Crime (Vienna, Austria: United Nations, October 2011), p. 13.
http://www.unodc.org/document…