A World Bank study cited in The Millennium Development Goals Report 2015 found that almost half of 155 countries examined lacked adequate data for monitoring poverty. And in sub-Saharan Africa, where poverty is most severe, 61 per cent of countries lacked data for monitoring poverty trends. Vital statistics disaggregated by geographical region, ethnicity, disability and other characteristics are also lacking. Overall, in spite of progress made in the last 15 years, systematic statistics are lacking on the size, geographical distribution and characteristics of vulnerable populations in developing regions.