According to "The Progress of Nations," published by UNICEF, Nigeria is one of 10 countries in the world with the worst child survival rates. Child mortality was estimated at 191 per 1000 live births, which varied from 144/1000 in the southeast and 244/1000 in the southwest. The African regional average is 183/1000; the lowest rates are in Mauritius at 25/1000, and the worst are in Niger at 320/1000. The world average is 93/1000. Nigeria, compared to countries with the same level of economic development, ranks 16th out of 29 countries, which means child survival is very poor comparably. Nigeria ranked 22nd in nutrition in sub-Saharan Africa. 36% of Nigerian children were estimated to be underweight for their age, which is equal to the developing world average, but lower than the regional average of 31%. Nigeria has banned the distribution of free or low cost infant feeding formulas in maternity wards and had developed plans to control iodine deficiency disorders. Nigeria ranked 22nd on measles immunization and has 46% of its children immunized. The world average is 77%. 59% of Nigerian children attain a 5th grade primary education, which led to the rank of 11 in sub-Saharan Africa. The world average is 68%, and the African average is 48%. Primary school enrollment dramatically increased from 46% in 1960 to 76% in 1990, which was a time when the child population doubled. Lower educational ranking was attributed to the less than 1% of government expenditures on primary education. The total fertility rate is not known, even though Nigeria is one of the most populous countries. Maternal mortality is 800/100,000 live births, which is higher than the African average of 590 and much higher than the world average of 310. Nigeria ratified the Convention on Child Rights.