The monitoring of social, economic and environmental development requires the use of data that is comparable across countries and over time. For the first time in its 50-year history, the Yearbook presents data compiled from global sources maintained by Untied Nations agencies and other international organizations. It includes in a consistent manner the definitions and aggregation methods for all indicators. This completely revised edition hopes that the use of internationally comparable data and methodological transparency will trigger discussions on the benefits of following international statistical standards and methodologies at the national level.