Yes, figures can be manipulated to say almost anything.
But what motivation do you think the WHO has, for manipulating figures to pretend that outcomes from breastfeeding across the board, irrespective of country, region, class, socio-economic status, race, education level, etc. - any variable you like - are better than for formula feeding, if they are not?
Who would benefit from such a deception? A massive multi-national conglomerate like Nestle for example? Would they be giving the WHO backhanders? Probably not. Nestle's nearest competitors? Also not that likely. The International Association of Babies? More probable, but I'm not sure they've got either the funding or the organisational skillset to do the amount of bribery and corruption needed, to fiddle these particular figures. 