Ivyo bigaragara cane muri Afrika ya ruguru, aho ibitigiri vy'abapfasoni mu burimyi vyaduze kuva ku bice 30% gushika ku bice 43% hagati ya 1980 na 2010 (mu matohoza yabaye), co kimwe mu buseruko, aho vyavuye ku bice 35% gushika kuri 48%.
