Since its inception, one of the DAC's main functions has been to collect and publish statistics on aid flow. As noted in the Achievements section of this article, in 1969 the DAC's members adopted a criterion for calculating their aid contributions. They called the resulting measure of aid contributions Official Development Assistance (ODA). It has become widely used by other organisations, and scholars, as a general measure of aid; for example, the United Nations and the World Bank both commonly use ODA as calculated by the DAC as their measure of aid. This is in spite of the fact that it is not an entirely comprehensive measure. It includes only aid from government sources; aid from private sources, including NGO's, is not counted. About ten to fifteen percent of aid comes from private sources.