I have never heard of an illiterate adult in Gibraltar, so I'm surprised you list the literacy rate as 80%. What is this figure based on? I would guess 99%, as for the UK whose education system we share, would be more accurate. You should access the latest Gibraltar census.
You neglect to mention Spanish as a principal language of Gibraltar. Informal Street use Spanish is the main language heard from the largely bilingual population. English is for more formal registers and settings such as education, the workplace and official use. Moroccan spoken Arabic, which you do list, is a very distant 3rd, spoken only by immigrants numbering less than 5% of the population.