The 2007 edition of the Demographic Yearbook provides statistics on population size and composition, fertility, mortality, infant and foetal mortality, marriages and divorces. It also includes a detailed set of technical notes and footnotes explaining the sources, availability, timeliness, quality, reliability and coverage of the data presented. Data have been collected from national statistical authorities since 1948 through a set of questionnaires dispatched annually by the United Nations Statistics Division to over 230 national statistical offices. The primary sources of the data reported in the Demographic Yearbook are national population and housing censuses, population to related statistics from national administrative recording systems and population and household surveys reported by national statistical authorities.