http://millenniumindicators.un.org/unsd/mi/mi_goals.asp

In close collaboration with United Nations agencies and funds, the World Bank, IMF, and OECD, the United Nations Statistics Division coordinates data analysis and maintains the database containing the series related to the selected indicators, as well as other background series intended to supplement the basic 48 Millennium indicators, for more in-depth analysis. The figures presented in the database are from international series compiled by the various agencies. The availability of data necessary to calculate the indicators in each country depends on the capacities of the national statistical services. In many instances-when country data are not available or are affected by serious quality problems- estimates are used.