Chart of gibraltarians population by country of origin (1995)

Most Gibraltarian surnames are Mediterranean or British extraction. The exact breakdown is as follows:

Reference 1: Proportion (%) of family names on 1995 electoral register.

Reference 2: British, Spanish (excluding Minorcan), Italian, Portuguese, Maltese, Jewish, Minorcan, Other and Unassigned.

Source: http://en.wikipedia.org/wiki/Gibraltarian_people