the world bank and unhabitat have defined a cutoff point at which owneroccupied or rental housing is deemed unaffordable which has been used for tracking housing affordability over time as part of the agency s urban indicators programme housing is generally deemed affordable when a household spends less than pet cent of their income on housingrelated expenses such as mortgage repayments owners rent paymentsrenters and direct operational expenses such as taxes insurance and service payments except for latin america and the caribbean lac all subregions with significant slum prevalence recorded higher slum growth than the global urban population change average with the highest rates recorded in subsaharan africa ssa at per cent and southeast asia at per cent