The United Nations, which defines illiteracy as the inability to read and write a simple message in any language, has conducted a number of surveys on world illiteracy. In the first survey (1950, pub. 1957) at least 44% of the world's population were found to be illiterate. A 1978 study showed the rate to have dropped to 32.5%, by 1990 illiteracy worldwide had dropped to about 27%, and by 1998 to 16%. However, a study by the United Nations Children's Fund (UNICEF) published in 1998 predicted that the world illiteracy rate would increase in the 21st cent. because only a quarter of the world's children were in school by the end of the 20th cent. The highest illiteracy rates were found in the less developed nations of Africa, Asia, and South America; the lowest in Australia, Japan, North Korea, and the more technologically advanced nations of Europe and North America. Using the UN definition of illiteracy, the United States and Canada have an overall illiteracy rate of about 1%. In certain disadvantaged areas, however, such as the rural South in the United States, the illiteracy rate is much higher.