Linguistic diversity index

A footnote in the UNESCO report says only "Country for which a comparison between Ethnologue’s official language designation and IBE’s coded timetable information was possible, the result of which highlighted certain inconsistencies."

Haiti is listed with an index of 0.000, despite having both French and Haitian Creole as official languages.

The United States is listed with an index of 1/3, which mechanically implies that if you pick two people at random, at least 1/3 of the time one of them won't have English as their Mother tongue -- but that is very different from saying that they are not fluent in English.

The UNESCO report cites an earlier (2005) edition of the Ethnologue as its own source for this particular data.

The UNESCO report remains a useful independent source and benchmark year because of its wider availability.