Namibia is the most arid country south of the Sahara, with average rainfall varying from more than 600 mm in the north east to less than 25 mm in the Namib Desert to the west. Rainfall is erratic both temporally and spatially leading to large localised differences in precipitation and large annual fluctuations. Drought is a regular occurrence. Namibia's economy is heavily dependent on natural resources. Two-thirds of the 1.6 million population live in rural areas and are directly dependent upon the soil and living natural resources for their livelihoods.