Demographics of Belgium
Belgium's three official languages are Dutch, spoken by 59% of the population, French, spoken by 40%, and German, spoken by less than 1%. The vast majority of Belgium's population, 99%, is literate as defined by the Belgian government, i.e. capable of reading and writing in an official language by the time a citizen has reached the age of 15.
Partition of Belgium
The main reason for Brussels being mainly French-speaking was the low social prestige of the Dutch language in Belgium during the 19th century and the severe discrimination of both Dutch as a language and of the Flemings. French was, at that time, the language of the administration, government, culture, law and education. From 1880 onwards, more and more Dutch-speaking people became bilingual and passed only French on to their children, resulting in a rise of monolingual French-speakers after 1910. Halfway through the 20th century, the number of monolingual French-speakers carried the day over the (mostly) bilingual Flemish inhabitants. Only since the 1960s, after the fixation of the Belgian language border and the socio-economic development of Flanders was in full effect, could Dutch stem the tide of increasing French use.