By what percentage is the maize crop in Souther Africa going to decrease by 2030 ?
As a result of the U.S. federal government announcing its production target of of biofuels by 2017 , ethanol production will grow to by 2010 , up from 4.5 billion in 2006 , boosting ethanol 's share of maize demand in the U.S. from 22.6 percent to 36.1 percent .